Name: membrane sugars and cell identity
Uploaded: 2023-04-30T09:15:48.000Z
Duration: 1 min 30 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

9-12.B.1.4.a

Membrane Carbohydrates

Nach Lipiden und Proteinen sind Kohlenhydrate der dritte Hauptbestandteil biologischer Membranen.
Glykoproteine, Proteine mit gebundenen Kohlenhydraten, machen fast neunzig Prozent der Membrankohlenhydrate aus. Glykolipide sind die restlichen zehn Prozent.
Sowohl Glykoproteine als auch Glykolipide befinden sich auf der Außenseite der Membran und erfüllen verschiedene Funktionen, unter anderem als Antigene und Rezeptoren.
Kohlenhydrate werden durch N-glykosidische und O-glykosidische Bindungen an Proteine gebunden.
Die Bildung von N-glykosidischen Bindungen findet zwischen der Amidgruppe von Asparagin und einem Zucker wie N-Acetylglucosamin statt, während sich O-glykosidische Bindungen zwischen der Hydroxylgruppe von Serin oder Threonin und einem Zucker wie N-Acetylgalactosamin bilden.
Gebundene Kohlenhydrate schützen Proteine vor Proteasen, verändern ihre Gesamtladung und erhöhen ihre Wasserbindungskapazität.
Glykolipide werden aus Ceramid gewonnen – einem Sphingolipid. Glucocerebrosid oder Galactocerebrosid wird synthetisiert, wenn Glukose oder Galaktose an Ceramid bindet.
Ganglioside entstehen, wenn ein Oligosaccharid und Sialinsäure an Ceramid binden. Die negativ geladenen Ganglioside regulieren die Konzentration positiv geladener Calcium-Ionen und helfen so bei der Neurotransmission.

membrankohlenhydrate

Die Plasmamembran ist eine dynamische Barriere, die aus Lipiden, Proteinen und Kohlenhydraten besteht. Sie bildet ein Zentrum vieler zellulärer Prozesse, die für das Zellwachstum und das Überleben erforderlich sind. Kohlenhydrate verfügen über einzigartige strukturelle und chemische Eigenschaften, die der Plasmamembran helfen, ihre Funktionen effektiv auszuführen.

Membrankohlenhydrate haben keinen hydrophoben Bereich und befinden sich ausschließlich auf der äußeren Oberfläche der Zelle. Die Anlagerung von Zuckermolekülen oder die Glykosylierung von Proteinen erfolgt in den Lumina des endoplasmatischen Retikulums und des Golgi-Apparats, wohingegen die Glykosylierung von Lipiden nur im Lumen des Golgi-Apparats erfolgt. Wenn sich die Vesikel vom Golgi-Apparat lösen, befinden sich die Glykolipide und Glykoproteine daher in der inneren Schicht der Vesikelmembran. Wenn die Vesikel jedoch mit der Plasmamembran verschmelzen,  geraten die innere Schicht und die damit verbundenen Glykolipide und Glykoproteine auf die extrazelluläre Seite. Das ist der Grund, warum Glykoproteine und Glykolipide ausschließlich auf der äußeren Schicht zu finden sind. Einige eukaryontische und bakterielle Zellen scheiden große Mengen an Kohlenhydraten aus der Zelle aus und bilden so einen Zuckermantel um die Zelle, der als Glykokalyx bezeichnet wird.

Kohlenhydrate sind strukturell vielfältiger als Proteine und DNA. In Proteinen und DNA werden hauptsächlich kovalente Peptid- bzw. Phosphodiesterbindungen beobachtet. Im Gegensatz dazu kann jedes Zuckermolekül mehrere Arten kovalenter Bindungen bilden und ermöglicht die Bildung verschiedener Oligosaccharidstrukturen aus denselben Zuckermolekülen. Die strukturelle Vielfalt der Kohlenhydrate trägt dazu bei, jedem Zelltyp eine eigene Identität zu verleihen und spielt eine wesentliche Rolle bei verschiedenen Zellfunktionen. Abhängig vom Antigen auf der Oberfläche menschlicher Erythrozyten wird die Blutgruppe beispielsweise jeweils einer von vier Typen A, B, AB und 0 zugeordnet. Eine Person mit der Blutgruppe A hat das A-Antigen auf ihren Erythrozyten und bildet Antikörper gegen das B-Antigen. Eine Person mit der Blutgruppe B trägt das B-Antigen auf ihren Erythrozyten und hat Antikörper gegen das A-Antigen. Eine Person mit der Blutgruppe AB hat sowohl das A- als auch das B-Antigen auf ihren Erythrozyten und keine Antikörper gegen eines der beiden Antigene. Andererseits haben die Erythrozyten einer Person mit der Blutgruppe 0 weder A- noch B-Antigene, und diese Person hat Antikörper gegen beide.

Membrankohlenhydrate

Die Plasmamembran ist eine dynamische Barriere, die aus Lipiden, Proteinen und Kohlenhydraten besteht. Es ist das Epizentrum vieler zellulärer Prozesse, die für die ...

Education

Lehre

JoVE Core

Cell Biology

Zellbiologie

Unit 1

Einheit 1

Membrane Structure and Components

Membranstruktur und Komponenten

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

membrane sugars and cell identity

Membrane carbohydrates help give cells their surface identity and support plasma membrane function. The plasma membrane is a dynamic barrier made of lipids, proteins, and carbohydrates. These sugar chains have unique structural and chemical traits that help the membrane work properly for cell growth and survival.

Membrane carbohydrates do not have a hydrophobic region, so they are found only on the outer surface of the cell. Sugar addition, or glycosylation, of proteins occurs in the lumens of the endoplasmic reticulum and the Golgi apparatus. Glycosylation of lipids occurs only in the lumen of the Golgi apparatus.

When vesicles bud from the Golgi apparatus, glycolipids and glycoproteins are on the inner layer. After these vesicles fuse with the plasma membrane, that inner layer faces the outside of the cell. This is why glycolipids and glycoproteins are found only on the exoplasmic side.

Some eukaryotic and bacterial cells also release large amounts of carbohydrate outside the cell. This forms a sugar coat called the glycocalyx. Carbohydrates are more structurally diverse than proteins and DNA because each sugar molecule can form multiple kinds of covalent bonds. That allows many different oligosaccharide structures to form from the same sugars.

This diversity helps each cell type have a distinct identity and supports many cellular functions. A clear example is human red blood cell antigens, which determine blood groups A, B, AB, and O. Type A blood has A antigen and anti-B antibodies, type B has B antigen and anti-A antibodies, type AB has both antigens and no antibodies against them, and type O has neither antigen but carries antibodies to both.

Membrane Sugars and Cell Identity

what are membranes?

Was sind Membranen?

A cell&#39;s plasma membrane demarcates the cell&#39;s borders and determines the nature of its interaction with the environment. Cells exclude certain ...

membrane fluidity

Membranfluidität

Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of ...

fluid mosaic model

Fluid-Mosaik-Modell

Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane ...

membrane lipids

Membranlipide

Lipids are an essential component of all biological membranes. The average lipid content in mammalian membranes is 50%, though it can be as low as 20% in ...

asymmetric lipid bilayer

Die asymmetrische Lipiddoppelschicht

Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. ...

membrane asymmetry regulating transporters

membrane-asymmetry-regulating-transporters

Membranasymmetrie regulierende Transporter

Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
...

membrane carbohydrates

The plasma membrane is a dynamic barrier composed of lipids, proteins, and carbohydrates. It is the epicenter of many cellular processes required for cell ...

membrane proteins

Membranproteine

Plasma membranes have integral transmembrane proteins involved in facilitated transport. These proteins are collectively referred to as transport ...

lipids as anchors

Lipide als Anker

In the plasma membrane, the lipids forming the bilayer can also act as an anchor to tether proteins to the membrane. The three main types of lipid anchors ...

single-pass transmembrane proteins

Single-Pass-Transmembranproteine

Integral membrane proteins are tightly associated with the cell membrane and play a crucial role in cell communication, signaling, adhesion, and transport ...

multi-pass transmembrane proteins and &#946;-barrels

multi-pass-transmembrane-proteins-and-barrels

Multi-Pass-Transmembranproteine und β-Barrels

In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an ...

detergent purification of membrane proteins

detergent-purification-of-membrane-proteins

Reinigung von Membranproteinen mit Detergentmoleküleien

Detergents are used to purify the integral proteins of the membrane. The hydrophobic portion of the detergent can replace membrane phospholipids while ...

protein diffusion in the membrane

Proteindiffusion in der Membran

Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion ...

membrane domains

Membrandomänen

The membrane domains concentrate specific lipids and proteins at one place within the membrane, which helps in cell signaling, adhesion, and other ...

mechanisms of membrane domain formation

Mechanismen der Membrandomänenbildung

Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains ...

mechanisms of membrane-bending

Mechanismen der Membranbiegung

The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by ...

key terms and concepts

Learn how membrane carbohydrates stay on the cell surface, form the glycocalyx, and help determine blood group identity in human red blood cells.

Membrane Sugars and Cell Identity | JoVE K12

cell biology

JoVE Core Zellbiologie veranschaulicht komplexe zelluläre Prozesse in leicht verständlichen und dennoch umfassenden animierten Videolektionen. Diese Sammlung konzentriert sich auf die wesentlichen Bestandteile und Funktionen von Zellen, einschließlich Organellen und Membranen, Zelltransport und Zellenergie. Ergänzt wird sie durch Videos von Wissenschaftlern in Aktion, die die Anwendung der Zellbiologie in realen Forschungsexperimenten demonstrieren.

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.2

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, ...

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 ...

Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules ...

Peroxisomes

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

Introduction to the Cytoskeleton

Overview of the Cytoskeleton
The cytoskeleton is a network of protein filaments present within the cell, having three distinct filaments ...

Introduction to Actin

Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle ...

overview-of-myosin-structure-and-function

Overview of Myosin Structure and Function

Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with ...

Microtubules

Microtubules are the thickest cytoskeletal filaments with a diameter of 25 nm. In prokaryotic organisms, microtubules are commonly found in locomotory ...

The Structure of Intermediate Filaments

The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of ...

Types of Intermediate Filaments

The intermediate filaments are an essential component of the cytoskeleton. Presently six types of intermediate filament have been identified. Type I and ...

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 ...

pH Regulation in Cells

pH plays a critical role in maintaining normal cellular activities. It helps maintain the structure and function of various proteins, dictates the charge ...

Chemistry of the Cell

Introduction to Cellular Respiration

Organisms harvest energy from food, but this energy cannot be directly used by cells. Cells convert the energy stored in nutrients into a more usable ...

ATP Energy Storage and Release

ATP and Macromolecule Synthesis

Biological macromolecules are organic compounds, predominantly composed of carbon atoms. The carbon atoms are covalently bonded with hydrogen, oxygen, ...

1. Engage in evidence-based argument to relate a cell's function to the structure, function, and diversity of its components. Examples: Muscle cells have a large number of mitochondria, which create energy for contraction in the form of ATP. Some plant cells have a large vacuole which is used for storage and transport of excess nutrients in changing environments.

9-12.B.1.1

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form ...

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse ...

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Bacterial RNA Polymerase

Eukaryotic RNA Polymerases

General Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of ...

RNA Polymerase II Accessory Proteins

Transcription Elongation Factors

pre-mrna-processing-modification-of-pre-mrna-ends

Pre-mRNA Processing: Modification of pre-mRNA Ends

In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or ...

Pre-mRNA Processing: RNA Splicing

Chromatin Structure and RNA Splicing

Alternative RNA Splicing

Nuclear Export of mRNA

Transfer RNA Synthesis

Ribosomal RNA Synthesis

The Nucleolus

Additional Subnuclear Structures

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

tRNA Activation

Initiation of Translation

Termination of Translation

Improving Translational Accuracy

prokaryotic-transcriptional-activators-and-repressors

Prokaryotic Transcriptional Activators and Repressors

Nonsense-mediated mRNA Decay

The Eukaryotic Promoter Region

Molecular Chaperones and Protein Folding

Co-activators and Co-repressors

The Proteasome

Master Transcription Regulators

Regulated Protein Degradation

Regulated mRNA Transport

Proteins: From Genes to Degradation

mRNA Stability and Gene Expression

Cell Specific Gene Expression

MicroRNAs

MicroRNA (miRNA) are short, regulatory RNA transcribed from introns (non-coding regions of a gene) or intergenic regions (stretches of DNA present between ...

regulation-of-expression-occurs-at-multiple-steps

Regulation of Expression Occurs at Multiple Steps

Small interfering RNAs (siRNA)

Cis-regulatory Sequences

lncRNA - Long Non-coding RNAs

cooperative-binding-of-transcription-regulators

Cooperative Binding of Transcription Regulators

Epigenetic Regulation

Epigenetic changes alter the physical structure of the DNA without changing the genetic sequence and often regulate whether genes are turned on or off. ...

2. Obtain and evaluate information to explain the role of DNA and RNA in transcription and translation leading to protein synthesis and cellular function.

9-12.B.1.2

Nucleic Acids and Nucleotides

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#39;s genetic blueprint and have instructions for its ...

a. Use a model to describe the structure and sequence of DNA, including nucleotide structure, base pairing, and the structure of the helix.

9-12.B.1.2.a

Membrane Sugars and Cell Identity

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