Unit 1: Section 3 - Cell Structure and Membranes Flashcards
Name two parts of eukaryotic cell that prokaryotic cells don’t have?
Nucleus and mitochondria
Are prokaryotic or eukaryotic cells more complex?
Eukaryotic cells
Parts of a cell are called ?
Organelles
What surrounds a cell?
Plasma membrane
What is the function of the plasma membrane?
Regulates the movement of substances into and out of the cell
What two things would you find in the nucleus and what surrounds the nucleus?
Contains the nucleolus and chromatin, surrounded by the nuclear envelope
What is the nuclear envelope?
Double membrane which surrounds the nucleus
What is the function of lysosomes?
Contains digestive enzymes to digest invading cells and dead organelles
Where are ribosomes made in the cell?
In the nucleolus
Where are proteins made in the cell?
In the ribosomes
What are the two types of ER called?
Smooth and rough
What’s the function of the nucleus?
To control cell activity
What’s the function of the smooth ER?
Makes and transports lipids
What’s the function of the rough ER?
Processes and transports the proteins which gave been made by the ribosomes
What two organelles would a plant cell have but not an animal?
Chloroplasts and a cell wall
What us the function of the Golgi apparatus?
Modifies new proteins
What does the Golgi apparatus contain to transport protein in?
Vesicles
What in the cells produces energy through aerobic respiration?
Mitochondria
Do mitochondria have a single membrane?
No double
The inner membrane of a mitochondria fold into?
Cristae
What’s the inside of the mitochondria called?
Matrix
What will a cell contain more of if it uses a lot of energy ?
Mitochondria
What cells line the small intestine?
Epithelial cells
What are micro villi?
Finger like projections on the villi
Name two adaptations of epithelial cells in the small intestine?
- ) they have villi and then micro villi on the outside of the cell to increase surface area for food absorption
- ) lot of mitochondria to provide more energy energy for active transport
What are red blood cells adapted for and how are they adapted for this?
To carry oxygen, by having no nucleus to make room for oxygen-carrying haemoglobin
Name two ways that sperm cells are adapted for their function?
- ) they contain a lot of mitochondria to provide large amounts of energy
- ) they contain enzymes in their head which break down the plasma membrane of the egg cell
What’s the difference between magnification and resolution?
Magnification is how much bigger the image is than the specimen where as resolution is how detailed the image is
What’s the formula for magnification?
Magnification = length of image / length of specimen
How do you convert millimetres into micrometres?
Times by 1000
How do you convert micrometres into millimetres?
Divide by 1000
Name the three types of microscopes?
Light microscopes, transmission electron microscopes and scanning electron microscopes
How do transmission electron microscopes work?
Electromagnets focus a beam of electrons through the specimen, denser parts of the specimen absorb more electrons so they look darker on the image you end up with
How do scanning electron microscopes work?
Scan a beam of electrons across a specimen, knocking electrons of the specimen which are gathered by a cathode ray tube to form the image
What are two advantages of a light microscope?
- ) can see living cells
2. ) can see colour
What are two disadvantages of a light microscope?
- ) low magnification
2. ) poor resolution
What are two advantages of the transmission electron microscope?
- ) high magnification
2. ) good resolution
What are two disadvantages of a transmission electron microscope?
- ) thin specimen so electrons can pass through
2. ) can’t be used on living cells, must be in a vacuum
What are three advantages of a scanning electron microscope?
- ) 3D image
- ) can be used on thick specimen
- ) high magnification
What are two disadvantages of a scanning electron microscope?
- ) can’t be used on living cells, in a vacuum
2. ) lower resolution than a transmission electron microscope
A method of separating organelles from their cells is called?
Cell fractionation
What are three steps of cell fractionation ?
- ) homogenisation - breaking up the cell
- ) filtration - getting rid of the big bits
- ) ultracentrifugation - separating the cells
Name two ways cells are broken up during cell fractionation?
- ) vibrating the cells
2. ) or grinding the cells up
During cell fractionation why is homogenisation an important step?
Breaks up the plasma membrane and releases the organelles into the solution
In cell fractionation why is the solution kept ice cold?
To reduce the activity of enzymes that break down the organelles
In cell fractionation why is the solution isotonic ?
Some concentration of chemicals in the solution as the cells so there’s no net movement of water, to prevent the organelles bursting or shrivelling due to osmosis
What happens during filtration in cell fractionation?
The solution is passed through a gauze to separate any cell debris from the organelles
Why do you have to do ultracentrifugation for cell fractionation?
You have a solution containing different organelles and ultracentrifugation separates the organelles from each other
What happens during ultracentrifugation?
The cell fragments are put into test tube, and then into a centrifuge and spun at high speeds. The heaviest organelles go to the bottom and then are removed in a pellet. This is repeated until you have separated out all the organelles.
What order will you find organelles after ultracentrifugation (lysosome, ribosomes, mitochondria, nucleus, ERs)?
Nucleus, mitochondria, lysosomes, ERs and finally ribosomes`
What is the plasma membranes main function?
To control what substances enter or leave the cells
What are plasma membrane composed of?
Phospholipids, proteins and carbohydrates
What is the double layer of phospholipids called?
Bilayer
Is the head or tail of the phospholipid hydrophobic?
Head - hydrophilic
Tail - hydrophobic
How does the phospholipid bilayer form a barrier against water soluble substances?
They arrange them selves with the heads all facing out and the tail inwards, as this means the centre is hydrophobic the water soluble substances cant get through
What does the plasma membrane contain that allows it to detect when chemicals are released from other cells?
Receptor proteins
What does the plasma membrane contain that allows cell recognition?
Glycoproteins and glycolipids on the outside
What can fit between the phospholipids to make the bilayer more rigid and less fluid?
Cholesterol
Describe what a triglyceride looks like?
One glycerol molecules with three long tails of hydrocarbons (fatty acids)
What are the two types of fatty acid called and where does the difference lie in them?
Saturated and unsaturated, in the hydrocarbon tail
Whats the difference between saturated and unsaturated fatty acids?
Saturated have no double bonds between the carbon atoms, where as unsaturated does
What reaction are triglycerides formed by?
Condensation reactions
What bond forms between glycerol and fatty acids?
Ester bond
How is triglyceride formed from 3 fatty acids and a glycerol molecules?
Each fatty acids bonds with an OH on the glycerol, taking out H20 and leaving just the O between them
Whats the difference between phospholipids and triglycerides?
Phospholipid only have two fatty acids and instead of the last fatty acid have a phosphate group
Is the fatty acid or the phosphate group which is hydrophobic?
Phosphate group - hydrophilic
Fatty acid - hydrophobic
What is the test called you can do for lipids?
Emulsion test
How do you do the emulsion test for lipids?
Add ethanol to it and then shake it, add it to water and any lipid will show up as a milky emulsion
What is diffusion?
The net movement of particles from an area of high concentration to an area of lower concentration
During diffusion to molecules only move from an area of high concentration to an area of lower concentration??
No they move both ways just the net movement is towards the lower concentration
What is meant by along the concentration gradient?
The path of the molecules from the high concentration to the low
What does diffusion is a passive process mean?
No energy I needed for it to happen
Can oxygen and carbon dioxide diffuse across the phospholipid bilayer?
Yes as they are small enough to
What three things affect the rate of diffusion and how?
- ) concentration gradient - steeper the faster the rate of diffusion
- ) thickness of exchange surface - thinner the faster the rate of diffusion
- ) surface area - larger the faster the rate of diffusion
What is osmosis?
The diffusion of water molecules across a partially permeable membrane, from an area of high water potential to an area of lower water potential
What water potential does water have?
zero
Why is water potential of a solution always negative?
Adding anything to water will lower its water potential, and so it decreases from zero and becomes negative
What is isotonic?
When two solutions have the same water potential
What happens when a cell I placed in a solution with a higher water potential than it?
Water will move in my osmosis causing the cell to swell eventually burst
What I facilitated diffusion?
Net movement of particles from an area of higher concentration to an area of lower concentration using carrier proteins and channel proteins
Why do some molecules have to use facilitated diffusion?
They are too large to fit through the phospholipid bilayer or they are charged
Name two transport proteins?
Carrier and channel
Do carrier proteins transport large molecules or charged atoms?
Large molecules
How do carrier proteins transport large molecules?
The molecule attaches to the carrier protein in the membrane, the protein changed shape and the molecule is released on the opposite side
Are charged particles transported through carrier or channel proteins?
Channel
How do channel proteins transport charged atoms?
They form pores in the membrane for charged atoms to diffuse through
What is active transport?
Uses energy to move molecules and ions across the plasma membrane, against the concentration gradient
What two transports are used in active transport?
Carrier and co transporters
How are carrier proteins used in active transport?
A molecules attaches to it, the protein changes shape and releases the molecule on the opposite side. However energy is needed to move the molecules against the concentration gradient
How do co transports transport molecules against the concentration gradient?
They bind two molecule at the time. It uses he concentration gradient of one of the molecules to move the other against its own concentration gradient
Name two molecules that uses co transporters?
Sodium ions and glucose, to transport glucose against the concentration gradient
What is the stage 1 absorption of glucose during digestion?
When the carbohydrates are first broke down there is a high concentration of glucose in the small intestine so its just moves by diffusion across the epithelial cells and into the blood
Why do we have to use both diffusion and active transport to absorb glucose?
If we only used diffusion, when the concentrations were equal we wouldn’t absorb the rest of the glucose, active transport allows us to do this
How is the concentration gradient of sodium ions increased using the sodium potassium pump?
The sodium potassium pump transports sodium ions out of the small intestine epithelial cells and into the blood. Decreasing the concentration of sodium ions in the epithelial cells, and so increasing the concentration gradient
Why does the sodium potassium pump need to increase the concentration gradient of sodium in the small intestine?
So that it can diffuse along its concentration gradient back to the blood via the co transporters carrying the glucose with it.
Is cholera a prokaryotic cell or a eukaryotic cell and why?
prokaryote - it is a much simpler, single celled organism
What is the flagellum?
A long, hair-like structure that rotates to make the bacteria move
Why do some bacteria have a capsule?
Helps to protect the bacteria from attack by the immune system
What does the toxin released by cholera cause the chloride ion protein channels to do and what is the effect of this?
It causes the chloride ion protein channels in the small intestine epithelial cells to open
Chloride ions then move into the small intestine, lowering the water potential
Water then moves out of the blood into the small intestine by osmosis
The big increase in water leads to bad diarrhoea and hydration
What is an oral rehydration solution?
A drink that contains large amounts of salt and sugars dissolved in water to try and treat diarrhoea
Why does an oral rehydration solution contain a lt of sodium ions?
To increases glucose absorption
Give one for and one against for testing new oral rehydration solutions on children
For - the disease mainly effects children so it must be shown to be effective in them
Against - children don’t decide if they want to do their parents do so it can be seem to be unfair
