Y12 MS - Cells (Complete) Flashcards
What is the function of the cell surface membrane?
To control the movement of substances in and out of the cell
What is the function of the cell wall?
To provide strength and support to the cell
What is the cell wall made up of in plants?
Cellulose
What is the function of the nucleus?
To control activity in the cell and contain genetic information
Why does the nucleus have small pores in the double membrane surrounding it (nuclear envelope) ?
To allow substances in and out of the nucleus e.g nucleotides for DNA replication
Where is the nucleolus found?
In the nucleus
What is the function of the nucleolus?
It is the site of ribosome production
What is the function of mitochondria (singular mitochondrion) ?
Site of aerobic respiration
What are cristae (singular crista) ?
Folds of the inner membrane of mitochondria
What is a matrix?
Within mitochondria, the matrix is a fluid containing enzymes required for aerobic respiration
What is the function of chloroplasts?
Site of photosynthesis
What is the stroma?
The fluid within the inner membrane of chloroplasts
What are thylakoids?
Membrane-bound compartments in chloroplasts containing chlorophyll which stack to form grana
What are grana (singular granum) ?
Structures formed by stacked thylakoids in chloroplasts
What are lamellae?
Thin and flat thylakoid membranes which join together grana in chloroplasts
What is the function of ribosomes?
Site of protein synthesis
What is the function of the smooth endoplasmic reticulum?
Processing and storing carbohydrates, lipids and steroids
What is the function of the rough endoplasmic reticulum?
Folding and processing proteins made by ribosomes
What is found on the surface of the rough endoplasmic reticulum?
Ribosomes
What is the function of the Golgi apparatus?
Modifying and packaging lipids and proteins (into Golgi vesicles)
Making lysosomes
What is the function of Golgi vesicles?
Transporting proteins and lipids across the Golgi apparatus and or to the cell membrane
What is the function of the cell vacuole?
To store cell sap to keep the cell turgid
What is the function of lysosomes?
To break down dead / damaged organelles or invading cells
What do lysosomes contain?
Hydrolytic enzymes called lysozymes
What is the cell wall made up of in fungi?
Chitin
Which organelles have a double membrane?
Nucleus
Chloroplasts
Mitochondria
How are prokaryotic cells different from eukaryotic cells?
Prokaryotic cell walls contain murein (a glycoprotein)
They have no nucleus - instead just a single circular DNA molecules free in the cytoplasm
Smaller ribosomes
No membrane-bound organelles in the cytoplasm
What additional structures do prokaryotic cells have?
One or more flagella
A capsule surrounding the cell
One or more plasmids
What size ribosomes are found in eukaryotic cells?
80S
What size ribosomes are found in prokaryotic cells, mitochondria and chloroplasts?
70S
What is the structure of ribosomes?
Ribosomes are made up of two subunits consisting of RNA and proteins
What is cell fractionation?
A process where cells are broken up and the different organelles they contain are separated out
What are the two stages of cell fractionation?
Homogenisation
Ultracentrifugation
What has to happen to the tissue before homogenisation can occur in cell fractionation? (With reasons)
The tissue is placed in a cold, buffered solution which has the same water potential as the tissue
Cold - Slows enzyme activity so that the cells and organelles are not broken down and damaged
Buffered - Maintains the pH so that the cells and organelles are not damaged and altered
Same water potential - Prevents osmosis so that the cells do not shrink or burst
What is the process of cell fractionation?
The tissue is placed in a cold (prevents enzyme activity), buffered (maintains the pH) solution with the same water potential as the tissue (prevents osmosis).
The tissue-containing solution is then placed in a homogeniser where the cells are broken open to produce a homogenate
This is then filtered to remove any large pieces of debris
The filtered homogenate is then placed in tubes and put in a centrifuge
The centrifuge is spun at a low speed, forcing the most dense organelles (nuclei) to the bottom of the tube to form a pellet while the remaining fluid called the supernatant lies on top
The supernatant is removed and spun again in the centrifuge, forcing the heaviest organelles to the bottom of the tube again, forming a pellet (mitochondria / chloroplasts)
This is repeated until all of the organelles / the desired organelles are separated
During ultracentrifugation, the organelles from a tissue sample are separated. in what order are they separated?
Most dense —> least dense
Nuclei
Mitochondria / chloroplasts
Lysosomes
Ribosomes
What is the difference between ribosomes in eukaryotic cells and prokaryotic cells?
In eukaryotic cells, ribosomes are larger (80s) and ribosomes in prokaryotic cells are smaller (70s)
Where can epithelial tissues be found?
Lining the surface of organs
What is a is the function of the capsule?
To protect the bacterium from other cells and help groups of bacterial stick together for further protection
A capsule is a structure in what kind of cell?
A bacterial cell
What is the function of a plasmid?
To possess genes that may aid the survival of bacteria in adverse conditions
In prokaryotic cells, what is the cell wall made up of?
Murein
A plasmid is a structure in what kind of cell?
A bacterial cell
The capsid is a structure in a ———
Virus
What is a capsid?
A protein coat enclosing the nucleic acid of a virus
Viruses have ———— ——— which are essential to allow the virus to identify and attach to a host cell
Attachment proteins
Why does an optical microscope have a low resolution
Because light has a longer wavelength than the distances involved in small cell structures
