Vanessas Lectures Flashcards
What are viruses?
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms
What is bacteriophage?
A virus which parasitizes a bacterium by infecting it and reproducing inside it. Bacteriophages are used in genetic research.
What are chromatins made up of?
About 50% protein and 50% DNA.
Are chromosomes packed randomly within the nucleus?
No they occupy discrete fields
True or False? The Nuclear envelope is a single membrane.
False the nuclear envelope is a double membrane (4 Layers of lipid bilayers)
Is the head of a lipid bilayer hydrophilic or hydrophobic?
Hydrophilic
Is the tail of a lipid bilayer hydrophilic or hydrophobic?
Hydrophobic
What needs to pass between the nucleus and the cytoplasm
RNA and Proteins. DNA never does and Lipids dont need to.
What are nuclear pores?
Large ring-shaped protein complexes. They go though both membranes of the nuclear envelope.
Where are the ribosomes made?
In the nucleolus
What are ribosomes made of?
Protein and RNA
What is the main function of the Nucleolus?
To make ribosomes
What are the functions of the nucleus?
Storing DNA and Ribosomal production, transcription, replication of DNA, and the processing the mRNA
What are histones?
Proteins that help to organise and pack DNA
What is the nucleolus?
A sub-section of the nucleus. Where ribosomes are made
What is the nucleoid?
A region within the prokaryotic cytoplasm where DNA is found.
What does the endomembrane system include?
The nuclear envelope, the endoplasmic reticulum, the Golgi Apparatus, lysosomes, vesicles, endosomes, vacuoles.
What does the endomembrane system not include?
The mitochondria, plastids
Do prokaryotic cells have an endomembrane system?
No
What does the endomembrane system do? (refer to slides to finish)
Trafficking of material
What are the two ways of targeting proteins to cellular compartments in the cell?
Post-Translational translocation and Co-translational translocation
What is cell biology the study of?
The structure and function of the cell
The term “cells” was coined in 1665 by who?
Robert Hooke
Cell theory was developed in the 1830s by who?
Schleiden and Schwann
What are the three premises of cell theory?
1) All organisms are composed of one or more cells.
2) Cells are the smallest living units of all living organisms.
3) Cells arise only by division of a previously existing cell.
What is Light microscopy?
A type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. The cells may be living or dead.
What is Fluorescence microscopy?
Can be used to study location of
specific proteins in the cell eg. Confocal microscopy eliminates out-of-focus background, giving
a sharper image.
How do we study cells?
Instead of focusing visible light on a
sample, electrons are focused on
the sample. Because electrons allow humans to see the smaller parts of cells.
What is Electron microscopy?
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination
What are the two forms of electron microscopy?
Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM).
What is scanning electron microscopy?
The study of surfaces of objects by measuring the scattered electrons. In this case the samples need to be coated with a conductive material and the samples are dead
What is transmission electron microscopy?
Where electrons are passed through a
sample and the transmitted electrons are detected. Cells are dead in this case.
What are the 3 domains of life?
Bacteria, Archaea, and Eukarya
What is Archaea?
These microorganisms lack cell nuclei and are therefore prokaryotes. They have distinct molecular characteristics separating them from bacteria
What is bacteria?
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals
What is Eukarya?
Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes, which have no membrane-bound organelles.
What are the main components of an animal cell?
A nucleus, the mitochondria, the Golgi apparatus, the endoplasmic reticulum, plasma membrane, ribosome, cytoskeleton, and peroxisome.
What are the main components of a plant cell?
Cell wall, nucleus, mitochondria, Golgi and ribosomes, vacuole, and chloroplasts.
How are Eukaryotes generally distinct from prokaryotes?
They contain a nucleus, have organelles and can be multicellular.
What is the function of the chromosome?
The compactness of chromosomes plays an important role in helping to organize genetic material.
How does the 2m of DNA get packed into each and every cell?
Due to the physical basis of chromosomal packing of successive rounds of coiling and looping. “Super coiling”
Which proteins are involved in packing of DNA?
Histone proteins. Histones proteins are also involved in opening of DNA
Chromatin is 50% what?
50% protein and 50% DNA.
True or False? Chromosomes are not packed randomly within the nucleus, but occupy discrete fields.
True
What is the Nuclear Envelope?
The nucleus is surrounded by a lipid membrane called the nuclear envelope. The nuclear envelope is a
double membrane. The pores regulate the passage of macromolecules like proteins and RNA, but permit free passage of water, ions, ATP and other small molecules.
What is a double membrane?
A membrane is a lipid bilayer, the plasma membrane (cell
membrane) is single membrane but a double membrane has two lipid bilayers. The nuclear envelope is a
double membrane
What needs to pass between
the nucleus and the cytoplasm?
Proteins and RNA
What are nuclear pores?
The nuclear pore is a protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and the cytoplasm. Nuclear pores are large ring-shaped protein complexes, nuclear pores go through both membranes of the nuclear envelope.
True or False? Nuclear pores are complex
True, they are made from > 456 individual
proteins
What is the Nucleolus?
A dark staining region of the nucleus
that contains very little DNA. The nucleolus makes ribosomal subunits from proteins and ribosomal RNA, also known as rRNA. It then sends the subunits out to the rest of the cell where they combine into complete ribosomes.
Functions of the nucleus?
- Storage of DNA
- Ribosomal production
- Transcription of DNA into
mRNA - Replication of DNA
- Processing of mRNA
What is the central dogma?
The ‘Central Dogma’ is the process by which the instructions in DNA are converted into a functional product.
Where does transcription take place in the cell?
The nucleus
Where does translation take place in the cell?
In the cytoplasm
True or False? Bacteria chromosomes are usually circular
True
Where is the DNA located in the bacterial cell?
The nucleoid
True or False? In bacterial cells translation and transcription occur at the different ends of the cell
False
What is the endomembrane system?
The system of membranes within a cell that exchange material either directly or via vesicular transport (works together to modify, package, and transport lipids and proteins)
What does the endomembrane system include?
Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vesicles, endosomes, vacuoles Plasma membrane
What does the endomembrane system not include?
mitochondria and
plastids (e.g. chrloroplasts)
True or False? Both eukaryotic and prokaryotic cells have an endomembrane system.
False, only eukaryotic cells have an endomembrane system.
What are some of the things an endomembrane system does?
The Trafficking of material, Production of proteins, Modification of proteins, Production of lipids, Specific chemical reactions, and Storage of molecules.
How are proteins trafficked around the cell?
Carrier proteins are used to transport proteins across cellular membranes such as the plasma membrane, endoplasmic reticulum and nuclear envelope.
What are signal peptides or signal sequence?
They are located on the N-terminus of some proteins and enable those proteins to find their correct location outside the cell membrane. The signal sequence tags the protein for transport through the cell membrane and out of the cell. “Codes them”
True or False? Different Signal Sequences Send Proteins to Different Locations
True
What s a signal sequence/peptide?
A string of amino acids that is apart of a protein sequence dedicated for localizing the protein to its correct cell compartment
What are the two types of targeting that occur to membrane-bound systems?
Post-translational translocation and Co-Translational translocation
What is Post-translational translocation?
The protein is translated entirely in the cytoplasm by a free ribosome, the signal sequence directs the protein to the appropriate compartment
What is Co-Translational translocation ?
The protein is initially translated by a free ribosome, The entire ribosome goes to the membrane, becoming a bound ribosome. The Protein translocates across the
membrane while being translated.
What is the endoplasmic reticulum?
A continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins .
What is the endoplasmic reticulum made up of?
Smooth er, rough er, the nuclear envelope, ribosomes, ER lumen, and cristae.
What is the difference between smooth and rough ER?
Both the smooth and rough endoplasmic reticulum help in the production and storage of proteins The main difference is that one contains ribosomes on it and the other does not. The rough endoplasmic reticulum (RER) has ribosomes on its surface. … The smooth endoplasmic reticulum (SER) does not contain ribosomes.
What are the functions of smooth ER?
Synthesis of lipids (including steroids) eg. Reproductive tissues, Metabolism of carbohydrates, Detoxification of drugs and poisons, and the Storage of calcium ions.
What are the functions of rough ER?
Serves as a site for translation of proteins that are
destined to be secreted or for the plasma membrane, it adds carbohydrates to proteins (glycoproteins), Produces lipids and new membranes, and sends proteins on to the Golgi apparatus via vesicles.
What are glycoproteins?
Glycoproteins are proteins that have sugars attached to them. They do many important jobs for the body, such as helping the immune, digestive, and reproductive systems.
What are vesicles in the cell?
Vesicles are a small, membrane-bound organelles that shuttle between other organelles, or between an organelle and the plasma membrane.
What is Vesicular transport?
Vesicles or other bodies in the cytoplasm move macromolecules or large particles across the plasma membrane. There are two types of vesicle transport, endocytosis and exocytosis. Both processes are active transport processes, requiring energy
What is the function of the Golgi Apparatus?
The Golgi apparatus follows the ER in processing proteins and other molecules. The Golgi apparatus is the “shipping and receiving centre” of the cell
What are the two models to explain movement of material through the Golgi apparatus?
The vesicular transport model and the Cisternal maturation model
What is the vesicular transport model?
Proteins move through the Golgi. Separate vesicles transport materials in both the forward
and reverse directions. The Cisterna remain static.
Return vesicles are required to ensure retention of enzymes
What is the Cisternal maturation model?
Individual cisternae of the Golgi mature, transporting
material in the forward direction, taking proteins with
them. Return vesicles are required to
ensure retention of enzymes
What does the Golgi apparatus do?
Sends material (proteins, lipids) to various places, Protein processing, and Carbohydrate manufacturing.
What is exocytosis?
Vesicle fusion with the plasma membrane
What is endocytosis?
Vesicle recovery from the plasma membrane
Exocytosis delivers what?
- the protein and carbohydrate contents to the outside of the cell
- lipids to the plasma membrane
- membrane proteins to the plasma membrane
Endocytosis retrieves what?
- the contents of the vesicle, including solutes and nutrients
- lipids from the plasma membrane
- membrane proteins
What are lysosomes?
Compartments where digestion (lysis) takes place, Contain proteases, nucleases, glycosidases, lipases etc
What is phagocytosis?
Phagocytosis is the process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
What is Pinocytosis?
A process by which liquid droplets are ingested by living cells.
What is the receptor-mediated endocytosis?
A process by which cells absorb metabolites, hormones, proteins – and in some cases viruses – by the inward budding of the plasma membrane
What is cisternae?
Sacs that make up the ER or Golgi apparatus
What is ER lumen?
The liquidy bit inside the ER
What are glycoproteins?
Proteins with sugars added to them
What are vesicles?
A small bubble of membrane used for shipping components around the cell
Proteins are moved through the cell via what?
Signal sequences
Proteins are translated in the cytosol via what?
Post-translational translocation
Proteins translated into a membrane enter via what?
Co-translational translocation
Material leaves the cell via what?
Exocytosis
Material enters the cell via what?
Endocytosis
What does the mitochondria do (simple)?
Turn fuel into ATP
What do chloroplasts do (simple)?
Turn light into fuel
True or False, both the mitochondria and chloroplasts have a similar evolutionary origins.
True
Is the membrane of the mitochondria a single or double membrane?
Double membrane