Name: maternal dna in mitochondria and chloroplasts
Uploaded: 2019-08-01T09:20:21.000Z
Duration: 1 min 29 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-1

Non-nuclear Inheritance

בתאים איקריוטיים, מיטוכונדריה ופלסטידות, קבוצת אברונים בתאי צמחים הכוללת כלורופלסטים, מתרבים באופן עצמאי בתוך הציטופלזמה, ולכל אחד מהם מערך גנטי ייחודי המנהל את הרבייה ואת התפקוד שלהם. הדנ"א של מיטוכונדריה ושל פלסטידות הוא בצורת מולקולות דנ"א מעגליות קטנות ומכונה דנ"א חוץ-גרעיני או דנ"א ציטופלזמי. כל אברון נושא עותקים רבים וזהים של הדנ"א שלו, לעומת הגרעין, שבדרך כלל מכיל רק שני עותקים של כל כרומוזום.יתרה מזאת, במהלך חלוקת התא, האברונים מופרדים באופן אקראי לתאי-בת חדשים, לכן הדנ"א החוץ-גרעיני אשר מועבר הלאה אינו מופיע לפי דפוס מוגדר. במהלך הרבייה בחיות וברוב הצמחים, הציטופלזמה בתוך הזיגוטה מגיעה מהביצית. לכן, למרות ששני ההורים תורמים באופן שווה לדנ"א הגרעיני, הדנ"א החוץ-גרעיני מועבר הלאה מהאם בלבד.משמע שתכונות מסוימות, כמו הפרעות מטבוליות שנוצרות כתוצאה ממוטציות בתוך המיטוכנדריה, ניתנות לאיתור באופן מטריאליניאלי. בנוסף, חלק מהתכונות הפיזיות של צמחים, כמו צבע העלה, נקבעות על ידי גנים חוץ-גרעיניים, וגם עוברות הלאה מהורה אחד בלבד.

מיקו, א. "גנים לא גרעיניים ותורשה שלהם". חינוך לטבע 1, מס '1 (2008). [<a href="https://www.nature.com/scitable/topicpage/non-nuclear-genes-and-their-inheritance-589">מקור</a>]

פטאנאן, אלכסנדר נ., טינג-הסיאנג וו, פיי-יו צ'יו ומייקל א. טייטל. 2016. "שינוי הגנום המיטוכונדריאלי." מטבוליזם של תאים 23 (5): 785–96. [<a href="https://doi.org/10.1016/j.cmet.2016.04.004">מקור</a>]

ירושה לא גרעינית

<div style="direction:rtl">רוב ה-DNA שוכן בגרעין התא. עם זאת, לחלק מהאברונים בציטופלזמה של התא, כגון כלורופלסטים ומיטוכונדריה, יש גם DNA משלהם. האברונים הללו משכפלים את ה-DNA שלהם ללא תלות ב-DNA הגרעיני של התא שבו הם שוכנים. תורשה לא גרעינית מתארת תורשה של גנים ממבנים אחרים מלבד הגרעין. מיטוכונדריה קיימות הן בצמחים והן בתאי בעלי חיים. הם נחשבים כמרכזי הכוח של תאים אוקריוטיים מכיוון שהם מפרקים גלוקוז ליצירת אנרגיה שמזינה את הפעילות התאית. DNA מיטוכונדריאלי מורכב מכ-37 גנים, ורבים מהם תורמים לתהליך זה, הנקרא זרחון חמצוני. כלורופלסטים נמצאים בצמחים ובאצות והם אתרי הפוטוסינתזה. פוטוסינתזה מאפשרת לאורגניזמים אלה לייצר גלוקוז מאור השמש. DNA של כלורופלסט מורכב מכ-100 גנים, שרבים מהם מעורבים בפוטוסינתזה. בניגוד ל-DNA כרומוזומלי בגרעין, הכלורופלסט וה-DNA המיטוכונדריאלי אינם עומדים בהנחה המנדלית שחצי החומר הגנטי של האורגניזם מגיע מכל הורה. הסיבה לכך היא שתאי זרע בדרך כלל אינם תורמים DNA של מיטוכונדריה או כלורופלסט לזיגוטים במהלך ההפריה. בעוד שתא זרע תורם בעיקר קבוצה הפלואידית אחת של כרומוזומים גרעיניים לזיגוטה, תא ביצית תורם את האברונים שלו בנוסף לכרומוזומים הגרעיניים שלו. זיגוטים (וכלורופלסטים בתאי צמחים) מקבלים בדרך כלל מיטוכונדריה וכלורופלסטים רק מתא הביצה; זה נקרא תורשה אימהית. ירושה אימהית היא סוג של ירושה לא גרעינית, או חוץ גרעינית. מדוע למיטוכונדריה ולכלורופלסטים יש DNA משלהם? ההסבר הרווח הוא התיאוריה האנדוסימיוטית. התיאוריה האנדוסימיוטית קובעת שהמיטוכונדריה והכלורופלסטים היו פעם פרוקריוטים עצמאיים. בשלב מסוים, הם הצטרפו לתאים איקריוטיים מארח ונכנסו למערכת יחסים סימביוטית שמיטיבה עם שני הצדדים.</div>

רוב הדנ"א שוכן בגרעין התא. עם זאת, כמה אברונים בציטופלסמה של התא - כגון כלורופלסטים ומיטוכונדריה - גם ...

Education

JoVE Core

Biology

ביולוגיה

Genetics

גנטיקה

Classical and Modern Genetics

גנטיקה קלאסית ומודרנית

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

maternal dna in mitochondria and chloroplasts

Maternal DNA in mitochondria and chloroplasts explains how some genes are inherited outside the nucleus. Most DNA is in the nucleus, but mitochondria and chloroplasts in the cell cytoplasm also carry their own DNA and can copy it independently of nuclear DNA.

Mitochondria are found in both plant and animal cells. They are called the powerhouses of eukaryotic cells because they break down glucose to make energy for cellular activity. Mitochondrial DNA has about 37 genes, and many help with oxidative phosphorylation, the energy-making process.

Chloroplasts are found in plants and algae. They are the sites of photosynthesis, which lets these organisms make glucose from sunlight. Chloroplast DNA has about 100 genes, and many of those genes help carry out photosynthesis.

This kind of inheritance does not follow the Mendelian idea that half of an organism’s genetic material comes from each parent. Sperm cells usually do not pass on mitochondrial or chloroplast DNA during fertilization. The egg cell contributes its organelles as well as its nuclear chromosomes, so zygotes and plant chloroplasts usually receive mitochondria and chloroplasts only from the egg. This is called maternal inheritance, which is a type of non-nuclear, or extranuclear, inheritance.

The main explanation for why these organelles have their own DNA is the endosymbiotic theory. It says mitochondria and chloroplasts were once independent prokaryotes. They later entered host eukaryotic cells and formed a symbiotic relationship that benefited both partners.

Maternal DNA in Mitochondria and Chloroplasts

maternal-dna-in-mitochondria-and-chloroplasts

genetic lingo

Genotype, Phenotype, and Inheritance

Genotype, phenotype, and inheritance help explain how traits and disease risk are passed from parents to offspring. In diploid organisms, including humans, most other animals, and many plants, somatic cells carry a duplicate set of chromosomes. These chromosome pairs are homologous, with similar length, centromere position, and gene locations. Diploid organisms inherit two versions of each gene, one from each parent. These versions are called alleles, and they sit at the same relative locus,...

punnett squares

Punnett Squares for Predicting Traits

Punnett squares help predict which traits offspring may inherit from two parents. They show possible genotypes, which are pairs of alleles, and can also show the chance of a phenotype, or visible trait, when the inheritance pattern is known. These grids work best for traits controlled by a single gene locus and passed on independently during meiosis. Punnett squares were developed in the early 1900s by Reginald Punnett. His work came after Gregor Mendel’s pea plant experiments revealed the...

monohybrid crosses

Mendel’s Pea Plant Inheritance Ratios

Gregor Mendel used pea plants to study how traits are passed from parents to offspring. His breeding experiments in the 1850s and 1860s showed that inheritance follows clear patterns. He crossed true-breeding plants that differed in one trait and found that dominant traits can hide recessive traits. Mendel focused on seven pea plant traits, and each trait had two forms controlled by a single gene locus. He noticed that true-breeding plants always produced offspring with the same phenotype, or...

dihybrid crosses

Mendel's Law of Independent Assortment

Mendel’s law of independent assortment explains how two traits can be inherited separately. Gregor Mendel tested this idea with pea plants that differed in two characteristics, such as pea color and pea shape. He used true-breeding parents that were homozygous for both traits but showed different phenotypes. In one example, Mendel crossed round, yellow peas with wrinkled, green peas. The parental generation had RRYY and rryy genotypes. Their first-generation offspring were all dihybrids,...

law of segregation

Mendel’s Pea Cross Ratios

Mendel’s pea plant crosses show how traits can disappear in one generation and return in the next. When he crossed plants, one parental trait sometimes seemed to vanish in the F1 generation and reappear in the F2 generation. Mendel used this pattern to explain why some traits are dominant and others are recessive. He proposed that traits are controlled by alleles, which are different versions of a gene. An organism inherits two copies of each gene, one from each parent. In his model, a...

law of independent assortment

Mendel’s Dihybrid Cross and Trait Ratios

Mendel’s dihybrid cross shows how two traits are inherited at the same time. A dihybrid cross is a cross in which both parents are homozygous for two distinct traits, and the F1 generation is heterozygous for both traits. Mendel used pea plants with round yellow peas and wrinkled green peas as an example. One parent had genotype YYRR, and the other had genotype yyrr. In the F1 generation, every plant showed the dominant traits, so the plants were YyRr and had yellow, round peas. The F2...

test cross

Using Test Crosses to Identify Genotypes

Test crosses are used to identify the genotype of an organism with a dominant trait. A genotype is the pair of alleles inherited for a gene, and alleles are different forms of the same gene. In diploid organisms, including humans, each gene usually has two alleles, one from each parent. An allele is recessive when its effect is hidden by another allele at the same gene location. Pea plants provide a clear example with flower color. White flowers are recessive, because one copy of the purple...

probability laws

Inheritance Risk with Sum and Product Rules

Inheritance risk can be calculated with the sum rule and the product rule. The sum rule applies to mutually exclusive events, or events that cannot happen at the same time. The product rule applies to independent events, or events that do not affect one another. These rules describe theoretical probability, which is the chance of an event before it happens. Empirical probability is different because it is based on events that have already occurred. These probability rules are useful in...

pedigree analysis

Reading Family Traits in Pedigrees

Pedigrees are family trees used to track how a trait passes through generations. They help scientists and students see whether a trait is dominant or recessive, whether it is autosomal or sex-linked, what genotypes family members may have, and what phenotypes may appear in future generations. For families with a history of inherited disease, this information can be important for family planning. In plants and animals, inheritance is often studied with crosses. Monohybrid crosses can show...

multiple allele traits

Blood Type and Allele Interactions

Multiple alleles can shape traits through blood type, sickle cell anemia, incomplete dominance, and codominance. Multiple allelism means a gene has three or more allelic forms. Diploid organisms, including humans, usually carry only two alleles for each gene, but many human genes exist in multiple forms in the population. Human blood type is a clear example of multiple allelism. The blood type gene has three alleles: I A , I B , and i. These alleles help determine which blood type a person has...

epistasis

Gene Masking in Rabbit Fur Color

Epistasis describes how one gene can mask or change the effect of another gene. In high school genetics, this helps explain why many traits do not follow a simple single-gene pattern. Instead, alleles at different locations can work together to shape the final phenotype. Mendel studied seven unrelated pea traits, but most traits involve multiple gene interactions. Epistasis often happens when one gene interferes with the expression of another gene. It can also occur when genes are part of the...

polygenic traits

Polygenic Traits in Human Height

Polygenic traits are traits controlled by more than one gene. Human height is a clear example of this kind of inheritance. Because many genes work together, the final trait can vary a lot from person to person. Researchers have found hundreds of loci, or gene locations, that influence height. There are likely many more that have not yet been identified. Many of these genes affect cartilage in the growth plates of the long bones in the arms and legs, either directly or indirectly. Height is...

pleiotropy

SOX10 and Multiple Traits in Pleiotropy

Pleiotropy is when one gene affects more than one trait. The SOX10 gene is a clear example because it can influence pigmentation, hearing, and intestinal movement. These traits may seem unrelated, but they can all be linked to the same gene change. In humans, a deleted region in SOX10 can cause Waardenburg Syndrome Type 4, or WS4. WS4 is an autosomal recessive disorder, which means a person usually inherits two altered copies of the gene. Common signs include a white forelock,...

nature and nurture

Genes and Environment Shape Height

Genes and environment both shape human height and other traits. Genes are the inherited instructions we get from our parents. Environment includes factors such as diet, stress, and social conditions. Many phenotypes, or observable traits, reflect both influences. Some also show up later in life, including cancer and other diseases. Height is a clear example of this interaction. Scientists estimate that 70-90% of height variation comes from genetic differences among people. The remaining 10-30%...

chromosomal theory of inheritance

How Genes Map to Chromosomes

Genes map to chromosomes, and this idea explains how Mendel’s inheritance patterns work. Gregor Mendel published his pea plant breeding results in 1866. He showed that physical traits follow predictable patterns. At the time, scientists did not yet know that genes existed. Mendel used the word "factors" for the hereditary units he studied. The details behind Mendel’s laws of segregation and independent assortment were still unknown for many years. In the late 1800s, better microscopes and...

non-nuclear inheritance

Maternal DNA in mitochondria and chloroplasts explains how some genes are inherited outside the nucleus. Most DNA is in the nucleus, but mitochondria and chloroplasts in the cell cytoplasm also carry their own DNA and can copy it independently of nuclear DNA. Mitochondria are found in both plant and animal cells. They are called the powerhouses of eukaryotic cells because they break down glucose to make energy for cellular activity. Mitochondrial DNA has about 37 genes, and many help with...

x-linked traits

X-Linked Inheritance in Families

X-linked inheritance explains how traits on the X chromosome are passed through families. In most mammalian species, females have two X sex chromosomes, while males have one X and one Y. A mutation on one X chromosome may be masked in females by a normal allele on the other X. In males, that same mutation is more likely to show because there is no second normal X to balance it. Traits caused by changes on the X chromosome are called X-linked traits. Color blindness is a well-studied example.

sex-linked disorders

X- and Y-Linked Disorder Patterns

X- and Y-linked disorders come from mutations in genes on the sex chromosomes. These genes, like those on autosomes, are needed for normal body function. When a mutation causes a biological problem, the condition is called sex-linked. Y-linked disorders come from changes in the Y chromosome. They affect only males, because only males carry a Y chromosome. Mutations in this small chromosome can affect male sexual function and secondary sex characteristics. One example is Y-chromosome...

x-inactivation

Barr Bodies and X-Chromosome Balance

Barr bodies and X-chromosome balance help explain how female mammalian cells control gene activity from the X chromosome. The human X chromosome carries far more genes than the Y chromosome. Because males usually have one X chromosome and females have two, females would make twice as many of some proteins without a control system. To prevent that imbalance, female mammalian cells inactivate nearly all the genes on one X chromosome during early embryonic development. The inactive X condenses...

key terms and concepts

Explore how mitochondria and chloroplasts pass DNA through maternal inheritance, and why organelle genes do not follow standard Mendelian inheritance.

Maternal DNA in Mitochondria and Chloroplasts | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS3-1.

myJoVE Corporation

DNA as a Genetic Template

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

DNA Packaging

Organization of Genes

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA ...

The Nucleosome

DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside ...

Chromatin Packaging

Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 ...

Karyotyping

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread ...

Histone Modification

The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational ...

Spreading of Chromatin Modifications

The histone&#160;proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are ...

Lampbrush Chromosomes

In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, R&#252;ckert observed LBCs in shark egg cells and coined the ...

Polytene Chromosomes

Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in ...

Histone Variants at the Centromere

Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as &#8220;mutant&#8221; forms that ...

Inheritance of Chromatin Structures

Epigenetics is the study of inherited changes in a cell&#39;s phenotype without changing the DNA sequences. It provides a form of memory for the ...

Euchromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions ...

Heterochromatin

chromatin-position-affects-gene-expression

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the ...

Genetics of Organisms

Mendelian Genetics
Evolution is caused by changes in the genetic composition of populations. In the field of population genetics, scientists model this ...

REF and WEF Fly Genetics
ExpandTo prepare for the experiment, be sure to obtain cultures of Drosophila melanogaster at least two weeks ahead of the ...

REF and WEF Fly Genetics
ExpandNOTE: At your station, you should have four vials of flies. They will be labeled as male or female. They will also be ...

Genetic Lingo

Overview

An organism is diploid if it inherits two variants, or alleles, of each gene, one from each parent. These two alleles constitute the genotype ...

Punnett Squares

Overview

A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait&#x2019;s inheritance pattern ...

Monohybrid Crosses

Overview

In the 1850s and 1860s, Gregor Mendel investigated inheritance by performing monohybrid crosses in pea plants. He crossed two plants that were ...

Dihybrid Crosses

Overview

To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental ...

Trihybrid Crosses

Trihybrid Crosses
Some of Mendel&#8217;s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A ...

Law of Segregation

When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 ...

Law of Independent Assortment

While Mendel&#x2019;s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how ...

Test Cross

Alleles are different forms of the same gene. Humans and other diploid organisms inherit two alleles of every gene, one from each parent.

An allele is ...

Chi-square Analysis

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an ...

Pedigree Analysis

Overview

A pedigree is a diagram displaying a family&#x2019;s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or ...

Nature and Nurture

Many human characteristics, like height, are shaped by both nature&mdash;in other words, by our genes&mdash;and by nurture, or our environment. For ...

Probability Laws

Overview

The probability of inheriting a trait can be calculated using the sum and product rules. The sum rule is used to calculate the probability of ...

background-and-environment-affect-phenotype

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as ...

Multiple Allele Traits

The Concept of Multiple Allelism

Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, ...

X and Y Chromosomes

Among mammals, the gender of an organism is determined by the sex chromosomes. Humans have two sex chromosomes, X and Y. Every human diploid cell has 22 ...

Chromosomal Theory of Inheritance

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of ...

The Y Chromosome Determines Maleness

The Y chromosome is a sex chromosome&#160;found in several vertebrates and mammals, including humans. In addition to 22 pairs of autosomes, the human ...

Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm⁠&mdash;such as chloroplasts and mitochondria⁠&mdash;also ...

The Ratio of X Chromosome to Autosomes

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined ...

Incomplete Dominance

Gregor Mendel&#39;s work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid ...

X-linked Traits

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be ...

Lethal Alleles

Agouti: A Lethal Allele
Lucien Cu&#233;not discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is ...

Sex-linked Disorders

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological ...

Epistasis

In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence ...

X-Inactivation

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, ...

Polygenic Traits

When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered ...

Dosage Compensation

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one ...

Pleiotropy

Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause ...

Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. [Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.]

genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

Gene Families

Gene Evolution - Fast or Slow?

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

What is Meiosis?

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of ...

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for ...

Meiosis vs. Mitosis

Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, ...

Crossing over

Nondisjunction

Make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and or (3) mutations caused by environmental factors. [Clarification Statement: Emphasis is on using data to support arguments for the way variation occurs.] [Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.]

HS-LS3-2

Maternal DNA in Mitochondria and Chloroplasts

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