Topic 1 - Cell Biology Flashcards
1
Q
Which cells are eukaryotic vs prokaryotic?
A
Animal and plant cells = eukaryotic
Bacterial = prokaryotic
2
Q
Structures in both animal and plant cells ?
A
Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
3
Q
What is the function of the nucleus ?
A
- contains DNA coding for a particular protein needed to build new cells
- enclosed in nuclear membrane
4
Q
What is the function of cytoplasm ?
A
- where chemical reactions occur
- contains enzymes
- organelles are found in it
5
Q
What is the function of the cell membrane ?
A
- controls what enters and leaves the cell
6
Q
What is the function of mitochondria ?
A
- where aerobic respiration reactions occur, providing energy
7
Q
What is the function of ribosomes ?
A
- protein synthesis
- found on structure called the rough endoplasmic reticulum
8
Q
Organelles found only in plant cells ?
A
- chloroplasts
- permanent vacuole
- cell wall
9
Q
Function of chloroplasts ?
A
- where photosynthesis takes place providing food for the plants
- contains chlorophyll pigment which harvests the light needed for photosynthesis
10
Q
Function of the permanent vacuole ?
A
- contains cell sap
- found within cytoplasm
- improves cell rigidity
11
Q
Function of the cell wall ?
A
- made from cellulose
- provides strength to the cell
12
Q
What are structures on bacterial cells ?
A
- cytoplasm
- cell membrane
- cell wall
- Singular circular strand of DNA
- Plasmids
13
Q
Give 6 examples of specialized cells ?
A
- sperm cells
- Nerve body
- muscle cells
- root hair cells
- xylem cell
- phloem cell
14
Q
What are sperm cells specialized to do and how ?
A
- Sperm cells: specialised to carry the male’s DNA to the egg cell (ovum) for successful reproduction
• Streamlined head and long tail to aid swimming
• Many mitochondria (where respiration happens) which supply the energy to allow the cell to move
• The acrosome (top of the head) has digestive enzymes which break down the outer layers of membrane of the egg cell
15
Q
What are nerve cells specialized to do and how ?
A
Nerve cells: specialised to transmit electrical signals quickly from one place in the body to another
• The axon is long, enabling the impulses to be carried along long distances
• Having lots of extensions from the cell body (called dendrites) means branched connections can form with other nerve cells
• The nerve endings have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters. These allow the impulse to be passed from one cell to another.
16
Q
What are muscle cells specialized to do and how ?
A
Muscle cells: specialised to contract quickly to move bones (striated muscle) or simply to squeeze (smooth muscle, e.g found in blood vessels so blood pressure can be varied), therefore causing movement
• Special proteins (myosin and actin) slide over each other, causing the muscle to contract
• Lots of mitochondria to provide energy from respiration for contraction
• They can store a chemical called glycogen that is used in respiration by mitochondria
17
Q
What are root hair cells specialized to do and how ?
A
Root hair cells: specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots
• Have a large surface area due to root hairs, meaning more water can move in
• The large permanent vacuole affects the speed of movement of water from the soil to the cell
• Mitochondria to provide energy from respiration for the active transport of mineral ions into the root hair cell
18
Q
What are xylem and phloem cells specialized to do and how ?
A
- Xylem cells: specialised to transport water and mineral ions up the plant from the roots to the shoots
• Upon formation, a chemical called lignin is deposited which causes the cells to die. They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
• Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water - Phloem cells: specialised to carry the products of photosynthesis (food) to all parts of the plants
• Cell walls of each cell form structures called sieve plates when they break down, allowing the movement of substances from cell to cell
• Despite losing many sub-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells.
19
Q
Light microscope ?
A
- 2 lenses : objective, eyepiece
- objective lens produces a magnified image, which is then magnified and directed into the eye by the eyepiece lenses
- approx magnification of x200 and a resolving power (resolution : ability to distinguish between 2 points) of 200nm
- used to view tissues, cells and large sub cellular structures
20
Q
A
21
Q
When were the first cells of a cork observed and by who ?
A
1965, using a light microscope
- Robert Hooke
22
Q
Electron microscope ?
A
- developed in the 1930s
- view deep inside sub cellular structures
- electrons used to form and image because they have a smaller wavelength
2 types : - scanning, creates 3D images
- transmission, creates 2d images detailing organelles
- magnification of up to x2,000,000 and a resolving power of 10nm(SEM) and 0.2nm(TEM)
23
Q
Magnification of a light microscope equation ?
A
Magnification of the eyepiece lens x magnification of the objective lens
24
Q
Size of an object equation ?
A
Size of image/magnificatoon
25
What are the 2 ways to grow microorganisms in the lab?
1. In nutrient broth solution- involves making a suspension of bacteria to be grown and mixing with sterile nutrient broth (the culture medium), stoppering the flask with cotton wool to prevent air from contaminating it and shaking regularly to provide oxygen for the growing bacteria.
2. On an agar gel plate- the agar acts as the culture medium, and bacteria grown on it form colonies on the surface.
Making the plate:
• Hot sterilised agar jelly is poured into a sterilised Petri dish, which is left to cool and set
• Wire loops called inoculating loops are dipped in a solution of the microorganism and spread over the agar evenly
• A lid is taped on and the plate is incubated for a few days so the microorganisms can grow (stored upside down)
26
What steps must occur when culturing microorganisms and why ?
1. Petri dishes must be sterilized, could be contaminated with other microorganisms which might be dangerous or compete with the desired bacteria
2. Inoculating tubes passed through a flame to sterilize, kills unwanted microorganisms
3. Sides of Petri dish must be sealed (but not completely), stops airborne microorganisms but sealing all the way could result in harmful anaerobic bacteria growing
4. Should be stored upside down, prevents condensation from disrupting growth
5. Should be incubated at 25 degrees, higher temps = more likely that bacteria could be harmful for humans
27
Calculation for the number of bacteria in a population after a certain time ?
Bacteria at beginning x 2 ^number of divisions = bacteria at end
28
Method to test the effects of different antibiotics on bacteria ?
1. Soak the paper discs in different types/concentrations of antibiotics and place on an agar plate evenly spread with bacteria. One disc should be a control, soaked in sterile water. There should be no death of bacteria with this disc- showing only the type of antibiotic affects the size of the inhibition zone (the clear area left when they die).
2. If the bacteria are resistant to the antibiotic they will not die, but non-resistant will die, leaving an inhibition zone.
3. Leave the plate at 25 degrees for 2 days.
4. The zone of inhibition can be measured- the bigger it is, the more bacteria are killed and therefore the more effective the antibiotic is.
29
What are the 3 stages of the cell cycle ?
Stage 1 - interphase - cell grows, organelles grow and increase in number, the synthesis of proteins occurs, DNA is replicated and energy stores are increased
Stage 2 - mitosis- chromosomes line up at the equator and the cell fibers pull each chromosome of the X to either side of the cell
Stage 3 - cytokinesis - / identical daughter cells form when the cytoplasm and cell membranes divide
30
What is a stem cell ?
An undifferentiated cell which can undergo division to produce many more similar cells, of which some will differentiate to have different functions
31
What are the 3 types of stem cells ?
- embryonic stem cells
- adult stem cells
- meristem in plants
32
Embryonic stem cells ?
- form when an egg and sperm fuse to form a zygote
- can differentiate into any type of cell in the body
- scientists can clone these cells and direct them to differentiate into almost any body cell
Could potentially be used to replace insulin producing cells for diabetes or new neural cells for Alzheimer’s or nerve cells for paralysis
33
Adult stem cells ?
- if found in bone marrow they can form many types of cells including blood cells
34
Meristem cells ?
- found in root and shoot tips
- can differentiate into any type of plant cell
- they can be used. To make clones of plants (desirable features, research or stopping extinction)
35
What is therapeutic cloning ?
- involves an embryo being produced with the same genes as the parents
- the embryo produced could then be harvested to obtain the embryonic stem cells
- these could be grown into any cells the patients need
36
Benefits vs problems of research with stem cells ?
Benefits :
- can be used to replace females or diseased body parts
- unwanted embryos from fertility clinics could be used as they would otherwise be discarded
- research into the process of differentiation
Problems :
- we don’t completely understand the process of differenciation
- removal of stem cells results in destruction of the embryo
- religious or ethical objections
- if the growing stem cells are contaminated with a virus an infection can be transferred to the individual
- money and time could be better spent into other areas of medicine
37
Diffusion definition ?
The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
38
Examples of diffusion in the body ?
- oxygen moves through the membranes of the structures in the lung called alveoli into the red blood cells and is carries across the body for respiration, carbon dioxide moves from the red blood cells into the lungs to be exhaled (gas exchange)
- urea moves from the liver cells into the blood plasma to be transported to the kidney for excretion
39
How does the concentration gradient affect the rate of reaction ?
The greater the difference in concentration, the faster the rate of diffusion because more particles are randomly moving down the gradient than are moving against it
40
How does temperature affect the rate of reaction ?
The greater the temperature, the greater the movement of particles, resulting in more collisions and therefore a faster rate of diffusion
41
How does the surface are of the membrane affect the rate of reaction ?
The greater the surface area the more space for particles to move through resulting in a faster rate of reaction
42
Calculation to find the volume ?
Length x width x height
43
Diffusion in the small intestine ?
Villi, digested food is absorbed over the membrane of these cells into the bloodstream
44
Diffusion in the gills ?
Water which has oxygen passes through the mouth and over the gills. Each gill has plates called gill filaments and upon these are gill lamellae which is where diffusion of oxygen into the blood and diffusion of carbon dioxide into the water takes place. Blood flows in one direction while water flows in the other
45
Diffusion in the roots ?
The roots are adapted to take up water and mineral ions. Roots have root hair cells with large surface areas which project into the soil
46
Diffusion in the leaves ?
Many different tissues to aid with gas exchange. Carbon dioxide diffuses through stomata for photosynthesis whilst oxygen and water vapor move out through them. The stomata are controlled by guard cells which change the size of the stomata (guard cells swell with lots of water and make the stomata larger)
47
Why is the adaption of having a large surface area beneficial and give examples of?
- the greater the surface area, the more particles can move through, resulting in a faster rate of diffusion
- lungs gas exchange in alveoli, small intestine millions of villi, fish gills with lamellae to increase surface area, leaves with a flattened shape and air spaces
48
Why is having an adaption of having a thin membrane beneficial ?
- provides a short diffusion pathway, allowing the process to occur faster
- lungs - alveoli and capillary walls
- small intestine - villi have a single layer of surface cell
49
Why is having an efficient blood supply/being ventilated a beneficial reaction ?
- creates a steep concentration gradient, so diffusion occurs faster
- lungs - the lungs constantly supply oxygen to make the blood from alveoli capillaries oxygenated, by exchanging it for carbon dioxide that can be breathed out, This is a constant process meaning the concentration gradient is always steep
Fish - Water flows in one direction and blood flows in the other which means that a steep concentration gradient is maintained as the concentration of oxygen is always much higher in the water so it will diffuse across
50
Osmosis definition ?
The movement of water from a less concentrated solution to a more concentrated one through a partially permeable membrane
51
What is the difference between an isotonic, hypertonic and hypotonic solution ?
Isotonic : the concentration of sugar in external solution is the same as the internal, no movement
Hypertonic : the concentration in the external solution is higher than the internal, water moves out
Hypotonic : the concentration of sugar in external solution is lower than the internal, water moves in
52
What is active transport ?
The movement of particles from an area where they are in lower concentration to an area where they are in higher concentration (against the concentration gradient)
53
Active transport in root hair cells ?
- they take up water and mineral ions from the soil
- mineral ions are usually in higher concentrations in the cells meaning diffusion cannot take place
- this requires energy from respiration to work
54
Active transport in the gut ?
- substances such as glucose and amino acids from your food have to move from your gut into your bloodstream
- sometimes there can be lower concentrations of sugar molecules in the gut than the blood meaning diffusion cannot take place
- active transport is required to move the sugar to the blood against its concentration gradient
