Name: how organelle genomes resemble bacteria
Uploaded: 2020-11-23T11:47:35.000Z
Duration: 2 min 16 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.5

comparing-mitochondrial-chloroplast-and-prokaryotic-genomes

Comparing Mitochondrial, Chloroplast, and Prokaryotic Genomes

Le cellule predatrici primitive, hanno fagocitato i batteri, che successivamente si sono evoluti in mitocondri, formando le cellule eucariotiche. Anche cianobatteri fotosintetici formarono relazioni simbiotiche con alcune di queste cellule eucariotiche e si evolsero infine nel cloroplasto. I genomi mitocondriali e cloroplasti attuali sono il risultato di questi genomi procariotici ancestrali.Rispetto ai genomi mitocondriali, i genomi dei procarioti attuali sono grandi, come in Escherichia coli, che contiene circa 5 milioni di coppie di basi e quasi 5, 000 geni. Il genoma mitocondriale umano è lungo quasi 17, 000 coppie di basi e contiene 37 geni, mentre il genoma mitocondriale di Arabidopsis thaliana, una pianta floreale, ha oltre 350, 000 coppie di basi ma contiene solo 57 geni. Rispetto ai genomi cianobatterici attuali come il genoma di synecocystis, che ha circa 3.5 milioni di coppie di basi e trasporta circa 3, 200 geni, il genoma del cloroplasto tra le piante terrestri, ha fino a 200, 000 coppie di basi e contiene da 120 a 135 geni.Anche se sono molto più piccoli, sia i genomi mitocondriali che quelli dei cloroplasti sono simili al genoma procariotico in diversi modi. Il loro DNA non si associa con le proteine istoniche ed è di solito circolare e a doppio filamento, simile a quello dei plasmidi batterici. Rispetto al genoma mitocondriale, il genoma cloroplastico assomiglia molto di più al genoma procariotico.Sia cloroplasto che i genomi procariotici hanno sequenze di DNA molto simili per promotori e terminatori di trascrizione. Inoltre, i genomi mitocondriali animali sono generalmente più piccoli del genoma mitocondriale nelle piante, poiché sia i genomi mitocondriali dei cloroplasti che quelli vegetali hanno introni che sono assenti nella maggior parte dei genomi mitocondriali animali.

<ol>
	<li>Smith, David Roy e Patrick J. Keeling. "Architettura del genoma mitocondriale e plastidiale: temi ricorrenti, ma differenze significative agli estremi." Atti dell'Accademia Nazionale delle Scienze 112, n. 33 (2015): 10177-10184.</li>
	<li> Shah, VC. "Evoluzione del genoma dei cloroplasti". Proc. Indian natn. Sci. Acad. B49 N0 6 (1983): 636-646.</li>
</ol>

confronto tra genomi mitocondriali, cloroplasti e procariotici

Gli odierni genomi mitocondriali e dei cloroplasti hanno mantenuto alcune delle caratteristiche dei loro procarioti ancestrali e hanno anche acquisito nuovi attributi durante la loro evoluzione all'interno delle cellule eucariotiche. Come i genomi procariotici, i genomi mitocondriali e dei cloroplasti non si legano con proteine simili agli istoni né mostrano un impacchettamento complesso in strutture simili ai cromosomi, come osservato negli eucarioti. A differenza delle divisioni cellulari mitotiche osservate nelle cellule eucariotiche, i mitocondri e i cloroplasti subiscono la fissione binaria e separano equamente il loro DNA negli organelli figli come osservato nei procarioti. Inoltre, i ribosomi sia nei mitocondri che nei cloroplasti sono sensibili agli antibiotici antibatterici.

I genomi procariotici hanno milioni di paia di basi e migliaia di geni; i genomi mitocondriali e dei cloroplasti, tranne che in alcune piante, sono molto più piccoli con un numero di coppie di basi nell'ordine di migliaia con poche centinaia di geni. Questa differenza nella dimensione del genoma si è verificata perché, durante l'evoluzione, parti significative dei genomi mitocondriali e dei cloroplasti primitivi sono state esportate nel nucleo. Questa esportazione di geni li ha resi dipendenti dal genoma nucleare per l’approvvigionamento di alcune proteine necessarie alla loro biogenesi.

I diversi percorsi evolutivi intrapresi da animali e piante hanno portato a differenze significative tra i genomi dei mitocondri animali e quelli dei mitocondri e dei cloroplasti vegetali. I genomi mitocondriali degli animali sono più piccoli dei genomi mitocondriali e dei cloroplasti delle piante. Inoltre, analogamente alla maggior parte dei genomi procariotici, i genomi mitocondriali degli animali non portano alcun introne. Tuttavia, gli introni sono presenti nei genomi sia dei mitocondri delle piante che dei cloroplasti. Rispetto ai genomi mitocondriali, i genomi dei cloroplasti mostrano meno variazioni in termini di dimensioni e struttura e contengono anche più geni. Ad esempio, il numero di geni presenti nel genoma dei cloroplasti dell'Arabidopsis thaliana è quasi il doppio dei geni presenti nel suo genoma mitocondriale. Inoltre, i genomi dei cloroplasti sono più simili alle loro controparti procariotiche rispetto al genoma mitocondriale poiché sono simili nelle sequenze regolatrici e nella disposizione di molti cluster di geni.

Confronto tra genomi mitocondriali, cloroplasti e procariotici

Gli attuali genomi mitocondriali e cloroplasti hanno conservato alcune delle caratteristiche dei loro procarioti ancestrali e hanno anche acquisito nuovi ...

Education

Didattica

JoVE Core

Molecular Biology

Biologia Molecolare

Unit 1

Unità 1

DNA Replication

Replicazione del DNA

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

how organelle genomes resemble bacteria

Mitochondrial and chloroplast genomes still keep several traits from their bacterial ancestors. They also show changes that happened after these organelles evolved inside eukaryotic cells. Eukaryotic cells are cells with a nucleus, while prokaryotes are cells without one.

Like prokaryotic genomes, mitochondrial and chloroplast genomes do not bind with histone-like proteins. They also do not show the complex chromosome-like packaging seen in eukaryotes. Mitochondria and chloroplasts divide by binary fission, and they split their DNA equally into daughter organelles, just as prokaryotes do. Their ribosomes are also sensitive to antibacterial antibiotics.

These organelle genomes are much smaller than prokaryotic genomes in most cases. Prokaryotic genomes often contain millions of base pairs and thousands of genes. Mitochondrial and chloroplast genomes usually contain only thousands of base pairs and a few hundred genes, except in a few plants. This size difference happened because many genes from early mitochondrial and chloroplast genomes moved to the nucleus during evolution.

That gene transfer made mitochondria and chloroplasts depend on the nuclear genome for some of the proteins they need to build and function. Evolution in animals and plants also produced important differences among their genomes. Animal mitochondrial genomes are smaller than plant mitochondrial and chloroplast genomes, and they usually do not contain introns, which are noncoding sections within genes. In contrast, introns are present in both plant mitochondria and chloroplasts.

Chloroplast genomes are usually more stable in size and structure than mitochondrial genomes. They also contain more genes. In Arabidopsis thaliana, the chloroplast genome has almost twice as many genes as the mitochondrial genome. Chloroplast genomes are also closer to prokaryotic genomes because their regulatory sequences and many gene clusters are arranged in similar ways.

How Organelle Genomes Resemble Bacteria

replication in prokaryotes

Prokaryotic DNA Replication Steps

Prokaryotic DNA replication copies the chromosome before a cell divides. In bacteria, this process starts at a specific DNA site called the origin of replication. From there, the cell builds new DNA strands using enzymes that match each base with its partner. The DNA double helix first opens so replication can begin. As the strands separate, each original strand serves as a template. New nucleotides are added in a set order, which helps the cell make an accurate copy of its genetic material. <br...

replication in eukaryotes

Eukaryotic DNA Replication Steps

Eukaryotic DNA replication copies the genome before a cell divides. In eukaryotes, this process happens in a controlled sequence so each new cell can receive genetic information. Replication begins at specific sites on the DNA called origins. The DNA is opened, and each original strand serves as a template, meaning it guides the building of a new complementary strand. This sets up two DNA molecules from one original molecule. The process then continues as enzymes add matching nucleotides to...

dna base pairing

DNA Base Pair Rules

DNA base pairing follows specific rules that help DNA carry genetic information. In DNA, the bases pair in a regular way, with adenine matching thymine and cytosine matching guanine. These pairs fit together because of their chemical shapes and bonding patterns. These base pairs also support accurate DNA replication. When DNA copies itself, each strand can guide the formation of a new partner strand using the pairing rules. Understanding base pairing helps explain how DNA stays organized and...

the dna replication fork

DNA Replication Stress and Fork Stalling

DNA replication stress and fork stalling can disrupt the copying of a cell’s genome. The replication fork is the Y-shaped site where DNA strands separate and new complementary strands are made at the same time. This linked unwinding and synthesis helps cells duplicate DNA efficiently and with fewer errors. In organisms with small circular DNA, such as E. coli, replication often begins at a single origin. That setup creates two replication forks that move in opposite directions from the opening...

proofreading

Proofreading in DNA Replication

Proofreading in DNA replication helps keep DNA copying accurate. It is a built-in check that reduces mistakes as new DNA is made. DNA polymerase is the enzyme that carries out this checking during replication. When it adds a wrong nucleotide, it can remove the error and replace it with the correct one. This correction step helps maintain the correct DNA sequence. Proofreading is an important part of DNA replication because it supports genetic accuracy. By catching mistakes as they happen, the...

dna helicases

Helicase Motor Proteins in DNA Unwinding

Helicase motor proteins help unwind DNA during key cell processes. They use energy from ATP hydrolysis, which is the breakdown of ATP to release usable energy. This movement lets helicases separate DNA strands when the cell needs access to the genetic code. These enzymes are involved in DNA replication, repair, recombination, and transcription. Helicases are found in all living organisms, but their structure, function, and movement can differ. In prokaryotes, the DnaB helicase moves along the...

the replisome

DNA Replication Teams in the Replisome

DNA replication depends on the replisome, a coordinated complex of proteins that copies DNA with high accuracy. This DNA replication machinery brings many parts together so the leading and lagging strands can be made at the same time. A key idea in this process is the trombone model, proposed by Bruce Alberts in 1980. In this model, a loop forms on the lagging strand when a primer is made. The loop grows as an Okazaki fragment is synthesized, then falls apart when that fragment is finished.

lagging strand synthesis

Okazaki Fragments in DNA Replication

DNA replication uses a leading strand and a lagging strand, and they are made at different rates. The leading strand starts first. The lagging strand starts later, moves more slowly, and is made in pieces. The two strands also differ in direction and starting steps. Leading strand synthesis follows the opening replication fork. Lagging strand synthesis goes in the opposite direction. The leading strand needs one RNA primer, while the lagging strand needs multiple RNA primers. After priming,...

mismatch repair

Fixing DNA Copying Errors

Mismatch repair helps fix DNA copying errors after replication. When DNA is copied, small mistakes can slip through. This repair system finds those mismatches and corrects them before they become permanent changes. The process depends on a group of mutator proteins. These proteins work together to detect the error, remove the incorrect section, and help replace it with the proper DNA sequence. In this way, mismatch repair supports the accuracy of genetic information. If the repair system does...

dna topoisomerases

How Topoisomerases Untwist DNA

DNA topoisomerases are enzymes that untwist DNA when it becomes overcoiled during cell processes such as DNA replication and transcription. They help regulate positive and negative DNA supercoiling without changing the nucleotide sequence. Clockwise overwinding creates positively supercoiled DNA, while counterclockwise underwinding produces negatively supercoiled DNA. Topoisomerases are grouped into two main types. Type I topoisomerases act on one strand of double-stranded DNA, and they...

telomeres and telomerase

How Telomerase Protects Chromosome Ends

Telomerase helps protect chromosome ends during eukaryotic DNA replication. When the final primer is removed, a single-stranded DNA fragment can remain at the end of the chromosome. That piece cannot be copied in the same way as the rest of the strand because there is no 3' end for new DNA to attach to. If this end piece is not replaced, chromosomal DNA is gradually lost each time a cell divides. The exposed single-stranded DNA can also trigger a DNA damage response from enzymes that detect it.

non-nuclear inheritance

Cytoplasmic Inheritance in Cells

Cytoplasmic inheritance explains how some traits are passed through cell structures outside the nucleus. These traits come from organelles such as mitochondria and chloroplasts. They do not follow the usual nuclear pattern of inheritance. Mitochondria and chloroplasts each contain their own DNA. Because of this, they can carry genetic information that affects cell function and certain visible traits. In high school biology, this topic helps explain why not all inherited traits come from...

animal mitochondrial genetics

Animal Mitochondrial DNA and Inheritance

Animal mitochondrial DNA has its own genome, separate from nuclear DNA. It is a double-stranded, closed circular molecule with about 20,000 base pairs. One strand is the heavy, or H-strand, because it is rich in guanine. The other is the light, or L-strand, because it is rich in cytosine. Compared with nuclear DNA, mitochondrial DNA has very little non-coding sequence. It also has no introns. Its genes are packed closely together, and some even overlap. The D-loop is the main non-coding...

comparing mitochondrial, chloroplast, and prokaryotic genomes

Mitochondrial and chloroplast genomes still keep several traits from their bacterial ancestors. They also show changes that happened after these organelles evolved inside eukaryotic cells. Eukaryotic cells are cells with a nucleus, while prokaryotes are cells without one. Like prokaryotic genomes, mitochondrial and chloroplast genomes do not bind with histone-like proteins. They also do not show the complex chromosome-like packaging seen in eukaryotes. Mitochondria and chloroplasts divide by...

export of mitochondrial and chloroplast genes

export-of-mitochondrial-and-chloroplast-genes

How Organelles Pass Genes to the Nucleus

Eukaryotic cells can carry three genetic systems: nuclear, mitochondrial, and chloroplast. Over time, many genes from mitochondria and chloroplasts have moved into the nucleus. In some plant species, this gene transfer is still happening. This movement has affected large parts of the genome in some organisms. About 18% of the Arabidopsis thaliana nuclear genome is thought to come from the chloroplast's cyanobacterial ancestor. In yeast, around 75% of the genome is derived from the...

single-strand dna binding proteins

How SSB Proteins Protect DNA Strands

Single-strand DNA-binding proteins, or SSB proteins, help protect DNA during replication. When double-stranded DNA is unwound, the two strands separate. SSB proteins bind to the exposed single strands and keep them stable. These proteins bind in a sequence-independent manner. That means the order of the nitrogenous bases does not have to follow a specific pattern for SSB proteins to attach. Their binding straightens single-stranded DNA and makes it more rigid. This support may help DNA...

key terms and concepts

See how mitochondrial and chloroplast genomes keep bacterial traits, why their DNA is smaller, and how plant and animal organelles differ.

How Organelle Genomes Resemble Bacteria | JoVE K12

molecular biology

Le video animazioni di JoVE Core Molecular Biology, organizzate in video lezioni, illustrano i processi molecolari cellulari in maniera chiara e concisa. Inoltre, nei video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

Texas Essential Knowledge and Skills

Biology

BIO.5

BIO.5.B

What are Cells?

Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium or trillions of them, ...

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Animal and Plant Cell Structure

Animal and plant cells not only differ in their structure, function, and mode of nutrition but also in how they reproduce, specialize, and organize into ...

Eukaryotic Evolution

The endosymbiont theory is the most widely accepted theory of eukaryotic evolution; however, its progression is still somewhat debated. According to the ...

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Chemistry of the Cell

The cell is chemically composed of water, organic molecules and inorganic ions.
Water
The polarity of the water molecule and its resulting hydrogen ...

Describe the scientific theory of cells (cell theory) and relate the history of its discovery to the process of science.

SC.912.L.14.1

Cell Size

Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (&#x3BC;m)and are considerably smaller than most ...

Eukaryotic Compartmentalization

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Prokaryotic Cells

Prokaryotes are small unicellular organisms that include the domains&#x2014;Archaea and Bacteria. Bacteria include many common organisms, such as ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

Endoplasmic Reticulum

Endoplasmic ReticulumThe endoplasmic reticulum (ER) is an extensive network of membranous sacs and tubules in eukaryotic cells, continuous with the outer ...

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Golgi Apparatus

As they leave the Endoplasmic Reticulum (ER), properly folded and assembled proteins are selectively packaged into vesicles. These vesicles are ...

Microtubules

There are three types of cytoskeletal structures in eukaryotic cells&#x2014;microfilaments, intermediate filaments, and microtubules. With a diameter of ...

Peroxisomes

Peroxisomes and mitochondria are two important oxygen-utilizing organelles in eukaryotic cells. Mitochondria carry out cellular respiration&#x2014;the ...

Gap Junctions

Multicellular organisms employ a variety of ways for cells to communicate with each other. Gap junctions are specialized proteins that form pores between ...

The Extracellular Matrix

In order to maintain tissue organization, many animal cells are surrounded by structural molecules that make up the extracellular matrix (ECM). Together, ...

Tissues

Cells with similar structure and function are grouped into tissues. A group of tissues with a specialized function is called an organ. There are four main ...

Plant Cell Wall

The plant cell wall gives plant cells shape, support, and protection. As a cell matures, its cell wall specializes according to the cell type. For ...

Plasmodesmata

The organs in a multicellular organism&#x2019;s body are made up of tissues formed by cells. To work together cohesively, cells must communicate. One way ...

What are Membranes?

A key characteristic of life is the ability to separate the external environment from the internal space. To do this, cells have evolved semi-permeable ...

Membrane Fluidity

Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are ...

Fluid Mosaic Model

The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of ...

What is an Electrochemical Gradient?

Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ...

Diffusion

Diffusion is the passive movement of substances down their concentration gradients&#x2014;requiring no expenditure of cellular energy. Substances, such as ...

Osmosis

Approximately 60% to 95% of the weight of living organisms is attributed to water. Therefore, maintaining appropriate water balance within cells is of ...

Tonicity in Animals

The tonicity of a solution determines if a cell gains or loses water in that solution. The tonicity depends on the permeability of the cell membrane for ...

Tonicity in Plants

Tonicity describes the capacity of a cell to lose or gain water. It depends on the quantity of solute that does not penetrate the membrane. Tonicity ...

Introduction to Membrane Proteins

The cell membrane, or plasma membrane, is an ever-changing landscape. It is described as a fluid mosaic where various macromolecules are embedded in the ...

Facilitated Transport

The chemical and physical properties of plasma membranes cause them to be selectively permeable. Since plasma membranes have both hydrophobic and ...

Primary Active Transport

In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or ...

Secondary Active Transport

One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this ...

Receptor-mediated Endocytosis

Overview

Receptor-mediated endocytosis is a process through which bulk amounts of specific molecules can be imported into a cell after binding to cell ...

Pinocytosis

Cells use energy-requiring bulk transport mechanisms to transfer large particles, or large amounts of small particles, into or out of the cell. The cells ...

Phagocytosis

Cells pull particles inward and engulf them in spherical vesicles in an energy-requiring process called endocytosis. Phagocytosis (&#x201C;cellular ...

Exocytosis

Exocytosis is used to release material from cells. Like other bulk transport mechanisms, exocytosis requires energy.

While endocytosis takes particles ...

Relate structure to function for the components of plant and animal cells. Explain the role of cell membranes as a highly selective barrier (passive and active transport).

SC.912.L.14.2

Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Compare and contrast the general structures of plant and animal cells. Compare and contrast the general structures of prokaryotic and eukaryotic cells.

SC.912.L.14.3

Overview of Microscopy Techniques

The early pioneers of microscopy opened a window into the invisible world of microorganisms. In 1830, Joseph Jackson Lister created an essentially modern ...

Introduction to Light Microscopy

The light microscope is an instrument used by researchers in many different fields to magnify specimens to as much as a thousand times their original ...

Overview of Electron Microscopy

The wavelengths of visible light ultimately limit the maximum theoretical resolution of images created by light microscopes. Most light microscopes can ...

phase-contrast-and-differential-interference-contrast-microscopy

Phase Contrast and Differential Interference Contrast Microscopy

Phase-Contrast Microscopes
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular ...

Confocal Fluorescence Microscopy

Confocal microscopy is an advanced microscopic technique. The prime advantage of the confocal microscope over other microscopy techniques is its ability ...

Introduction to Fluorescence Microscopy

Fluorescence microscopy is a very powerful analytical tool that combines the magnifying properties of light microscopy with visualization of fluorescence. ...

Super-resolution Fluorescence Microscopy

Super-resolution fluorescence microscopy (SRFM) provides a better resolution than conventional fluorescence microscopy by reducing the point spread ...

Compare and contrast structure and function of various types of microscopes.

SC.912.L.14.4

The present-day mitochondrial and chloroplast genomes have retained some of the characteristics of their ancestral prokaryotes and also have acquired new ...

the-tree-of-life-bacteria-archaea-eukaryotes

The Tree of Life - Bacteria, Archaea, Eukaryotes

The &#8220;tree of life&#8221; describes the evolution of life and the evolutionary relationships between organisms. The root of the tree is the common ...

The Anatomy of Chloroplasts

Green algae and plants, including green stems and unripe fruit, harbor specialized organelles called chloroplasts to carry out photosynthesis. They ...

Explain the evidence supporting the scientific theory of the origin of eukaryotic cells (endosymbiosis).

An Overview of Genetics and Disease

Many human diseases are associated with mutations or variations in genetic sequences. Some of these genetic variants are heritable, passed down from ...

Factors Affecting Illness

When a person&#39;s physical, emotional, intellectual, social development or spiritual functioning is compromised, this deviation from a healthy normal ...

Gene-Environment Interactions

Gene expression is influenced by environmental factors such as radiation, temperature, behavior, nutrition, and stress.
The range of reaction suggests ...

Dimensions of Health and Illness

The factors influencing the health-illness continuum can be internal or external and may or may not be under conscious control. They are related to the ...

Factors Affecting the Risk of Infection

The hosts&#39; susceptibility to infection depends on several factors. The integrity of the skin and mucous membranes helps protect the body against ...

Explain the significance of genetic factors, environmental factors, and pathogenic agents to health from the perspectives of both individual and public health.

SC.912.L.14.6

A. Cells have characteristic structures and functions that make them distinctive.

B. Processes in a cell can be classified broadly as growth, maintenance, reproduction, and homeostasis.

C. Life can be organized in a functional and structural hierarchy ranging from cells to the biosphere.

D. Most multicellular organisms are composed of organ systems whose structures reflect their particular function.

How Organelle Genomes Resemble Bacteria

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