Topic 2A: Cell Structure and Division Flashcards
Describe a lysosome
A round organelle surrounded by a membrane, type of golgi vesicle
What’s the function of a lysosome?
Contains digestive enzymes (lysozymes), used to digest invading cells or to break down worn out components
Describe a ribosome
A very small organelle that floats free in the cytoplasm or attached to rough ER, made of proteins/RNA
What’s the function of ribosomes?
Where proteins are made-protein synthesis
Describe rough ER
A system of membranes enclosing a fluid-filled space, covered in ribosomes
What’s the function of rough ER?
Folds and processes proteins that have been made in the ribosomes
Describe smooth ER
A system of membranes like RER, but without ribosomes
What’s the function of smooth ER?
Synthesis’s and processes lipids
Describe cell walls
A rigid structure surrounding cells in plants, algae and fungi mainly made of the carbs and cellulose
What’s the function of cell walls?
Supports cells and prevents them from changing shape
Describe the vacuole
Membrane-bound organelle found in the cytoplasm, contains cell sap (surrounding membrane is tonoplast)
What’s the function of the vacuole?
Helps maintain pressure inside the cells and keep it rigid (stops plant wilting)
How do Prokaryotic cells replicate?
Binary Fission
Explain binary fission
Step 1) Circular DNA replicates main DNA once, plasmids divide multiple times
Step 2) Cells get bigger the DNA loops move to opposite poles.
Step 3) Cytoplasm divides
Step 4) 2 daughter cells are produced, each cell has one circular DNA but multiple plasmids
Viruses aren’t cells, what are they?
Acellular, nucleic acids surrounding by a protein coat
What do viruses need to re-produce?
Host-cell
Once the virus is attached to the host-cell what does it do?
Inject their DNA/RNA into the host cell
What’s the magnification equation?
Magnification= size of image/real object size
How do you get from micrometers to nanometers?
X1000
How do you get from nanometers to micrometers?
/1000
What are microscope artifacts?
Things you see down a microscope that aren’t part of the cell, e.g fingerprints/bubbles
What’s a TEM microscope?
TEM use electromagnets to focus a beam of electrons this is transmitted through the specimen. Denser parts of the specimen absorb more electrons appearing darker
What’s a SEM microscope?
SEM’s scan a beam of electrons across a specimen. Knocking off electrons from the specimen (3D)
Describe the chloroplast
Small flattened structure found in plant cells and algal cells, double membrane, inside also thylakoid membranes, forming grana
What’s the function of chloroplast?
Where photosynthesis occurs
Describe the Golgi apparatus
A group of fluid-filled membrane-bound flattened sacs, vesicles are often seen at the edges
What’s the function of Golgi apparatus.
It processes and packages new lipids and proteins, also making lysosomes
Describe golgi vesicles
A small fluid filled sac in the cytoplasm, surrounded by a membrane
What’s the function of Golgi vesicles?
Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell
What is magnification?
How much bigger the image is than the original
What is resolution?
Resolution is how detailed the image is, how well the microscope distinguishes between 2 points
Name 2 types of microscope
Optical (light) microscopes and electron microscopes
Name the 2 types of electron microscopes
Transmission and scanning (TEM&SEM)
What do optical microscopes do?
Use light to form an image
What’s the max resolution of optical microscopes?
0.2um including ribosomes ER and lysosomes
What’s the max magnification of optical microscope?
1500x
What do electron microscopes do?
Use electrons to form an image
What’s the max resolution of a electron microscopes?
0.0002um
What’s the max magnification of an electron microscope?
1500000x
What are epithelial cells specialized to do?
Adapted to absorb food efficiently
How are epithelial cells specialized?
Have villi for increased SA, micro villi for increased SA and loads of mitochondria for lots of energy
How are red blood cells specialized?
No nucleus to make room for oxygen carrying haemoglobin
How are sperm cells specialized?
Lots of mitochondria providing large amounts of energy
What’s a tissue?
A group of cells grouped together to form tissues (Tissue-organ-organ system)
What type of organisms is a prokaryotic cell?
Single celled
What does the flagellum do?
Used for locomotion
What are plasmids?
Small loops of DNA, small loops aren’t part of the main circular DNA, for antibiotic resistance
What does the capsule do?
Capsule made up of secreted slime, protecting the bacteria from attacking other cells (immune system)
What is the cell wall in fungal cells made out of vs plant cells?
Fungal= chitin Plant= cellulose
Describe the cell-surface membrane
Membrane found on the surface of animal cells and just inside the cell wall of other cells, mainly made from lipids and proteins
What’s the function of the cell-surface membrane?
Regulates the movement of substances into and out of the cell
Also, has receptors on it that can respond to chemicals like hormones
Describe the nucleus
An organelle surrounded by a nuclear membrane (double membrane) nucleus contains chromosomes and nucleolus
What’s the function of the nucleus?
Controls the cell activities contains instructions to make proteins and ribosomes
Describe mitochondria
Oval-shaped, double membrane (inner folded unto cristae) inside is the matrix, containing enzymes for respiration
What’s the function of mitochondria?
Site of aerobic respiration, producing ATP
Name an advantage and disadvantage of SEMS microscopes?
Ad: can be used on thick specimens and can be 3D
Dis: Gives lower resolution than TEMS, only used on non-living specimens
Name an advantage and disadvantage of TEMS microscopes?
Ad: Give high resolution, show small objects
Dis: Can only be used on non-lining and thin specimens
What’s cell fractionation?
Separating organelles from the rest of the cell
What does homogenisation do and how do you do it?
Breaking up the cells, by vibrating or grinding the cells this breaks up the plasma membranes
Solution must be kept ice-cold, isotonic and a buffer solution added to maintain pH
Why do we filter the solution?
To get rid of larger cell debris
What does ultracentrifugation do and why?
Separating the organelles, poured into tube and put into a centrifuge spun on a low speed. Heavy organelles are spun off first, when you increase speed each time lighter organelles come of each time
What organelles are spun off, in which order?
Nuclei, mitochondria, lysosomes, ER and ribosomes
