Cell Biology Flashcards
(122 cards)
1
Q
What are all living things made out of?
A
Cells.
2
Q
Living things can either be..
A
Prokaryotic or Eukaryotic.
3
Q
Give two examples of eukaryotic cells.
A
Plants and animals.
4
Q
What do eukaryotic cells always contain?
A
- Cell membrane.
- Cytoplasm.
- Nucleus containing DNA.
5
Q
What is an example of a prokaryotic cell?
A
A bacterial cell.
6
Q
Compare the size of a bacterial cell to a plant/animal cell.
A
Bacterial cells are much smaller than plant/animal cells.
7
Q
What do prokaryotic cells always contain? What do prokaryotic cells sometimes contain?
A
Always:
- Cell wall.
- Cell membrane.
- Cytoplasm.
- Singular circular strand of DNA.
Sometimes:
- Plasmids. - (additional small rings of DNA)
8
Q
What are organelles?
A
Structures in a cell (that have different functions).
9
Q
What is a structure enclosed in a cell called?
A
An organelle.
10
Q
Cells are extremely small/big.
A
Small.
11
Q
Starting from centimetres, name the following (smaller) measuring units.
A
Centimetres (x10) - Millimetre (x1000) - Micrometre (x1000) - Nanometre.
12
Q
Starting from centimetres, name the previous (larger) measuring units.
A
Centimetres (/100) - Metres (/1000) - Kilometres.
13
Q
What is the function of the nucleus?
A
Contains DNA, and controls cell’s activities.
14
Q
What is the function of the cytoplasm?
A
Cytoplasm is a liquid substance where most chemical reactions take place. It contains enzymes, and organelles are found enclosed in it.
15
Q
What is the function of the cell membrane?
A
Controls the movement of substances in and out of the cell.
16
Q
What is the function of the mitochondria?
A
Where aerobic respiration occurs, providing energy for the cell.
17
Q
What is the function of the ribosomes?
A
Where protein synthesis occurs.
18
Q
What is the function of the chloroplasts?
A
Where photosynthesis takes place, providing food for the plant. Contains chlorophyll pigment, this pigment harvests the light needed for photosynthesis.
19
Q
What is the function of the permanent vacuole?
A
Contains cell sap, improves cell’s rigidity.
20
Q
What is the function of the cell wall?
A
Made from cellulose, provides strength for the cell.
21
Q
What are the extra sub-cellular structures only present in plant cells?
A
Cell wall, permanent vacuole, chloroplast.
22
Q
What are the sub-cellular structures present in animal cells?
A
Cell membrane, mitochondria, nucleus, cytoplasm, ribosomes.
23
Q
What is cell differentiation?
A
The process where a cell becomes specialised to its function, this involves the gaining of new sub-cellular structures.
24
Q
In animal cells, when do cells differentiate most?
A
early development stage.
25
In plant cells, when do cells differentiate?
throughout their whole life.
26
What are some examples of specialised cells in animals?
Nerve cells, muscle cells, sperm cells.
27
Why are sperm cells specialised?
Specialised to carry the male's DNA to the egg cell for successful reproduction.
28
How are sperm cells specialised?
- long tail, to aid swimming
- many mitochondria, to supply with energy
- acrosome possessing digestive enzymes, to break the outer layer of the egg cell's membrane
- only half the DNA in the nucleus
29
Why are nerve cells specialised?
Specialised to transmit electrical signals quickly from one place in the body to another.
30
How are nerve cells specialised?
- long axon, enabling impulses to be carried along long distances
- extensions called dendrites, enable branched connections to form with other nerve cells
- mitochondria, provide energy for the release of neurotransmitters in the synapses.
31
What are muscle cells specialised for?
specialised to contract quickly to move bones, causing movement.
32
How are muscle cells specialised?
- special proteins, slide over each other causing muscle to contract
- mitochondria, provide energy from respiration
- store a chemical called glycogen, used in respiration by mitochondria.
33
What are examples of specialised cells in plants?
root hair cell, xylem, phloem.
34
A root hair cell is specialised to..
to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots.
35
How are root hair cells specialised?
- large surface area due to root hairs, meaning more water can move in
- large permanent vacuole, affects the speed of movement of water from the soil to the cell
- mitochondria, energy for the active transport.
36
A xylem is specialised to..
to transport water and mineral ions up the plant from the roots to the shoots.
37
How are xylem cells specialised?
- lignin 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
38
Phloem cells are specialised to..
to carry the products of photosynthesis to all parts of the plant.
39
How are phloem cells specialised?
- cell walls form sieve plates, allowing movement of substances from cell to cell
- companion cells supply the phloem with mitochondria as the cells are alive.
40
What are stem cells?
undifferentiated cells.
41
In animals, when do almost all cells differentiate?
early stage
42
What is mitosis?
process that involves a cell dividing to produce 2 identical cells.
43
Red blood cells cannot divide and are replaced by..
adult stem cells
44
In mature animals, cell division mostly only happens to..
repair or replace damaged cells, as they undergo little growth.
45
What do adult stem cells replace?
red blood cells.
46
Do plant cells lose their ability to differentiate?
no
47
When were the first cells of a cork observed, by who and using what?
1665, Robert Hooke, light microscope
48
What are the qualities of a light microscope?
- two lenses, an objective and eyepiece
- objective lense produces magnified image, which is then magnified and directed into the eye by the eyepiece lense
- approx magnification x 2000 and resolving power of 200 nanometres
- use a beam of light to form an image
- used to view tissues, cells and large sub-cellular structures.
49
When was the electron microscope developed?
1930s
50
What did the electron microscope enable scientists to do?
view deep inside sub-cellular structures, such as mitochondria, ribosomes, chloroplasts and plasmids.
51
What are qualities of an electron microscope?
- electrons are used to form an image
- two types, scanning electron microscope and transmission electron microscope
- magnification up to x2 000 000 and resolving power of 10 nanometres (SEM) and 0.2 nanometres (TEM)
52
What images do transmission electron microscopes and scanning electron microscope give?
TEM - 2D
SEM - 3D
53
What is the equation of magnification?
size of image / size of object
54
What is the equation for the magnification of a light microscope?
mag of eyepiece lens x mag of objective lens
55
Where are stem cells found in animals?
bone marrow, embryos
56
Where are stem cells found in plants?
meristem
57
What do culture mediums contain?
carbohydrates for energy, minerals, proteins and vitamins.
58
What are the two ways to grow microorganisms in the lab?
nutrient broth solution, agar gel plate.
59
What does the nutrient broth solution include?
involves making a suspension of bacteria to be grown and mixing with sterile nutrient broth, stoppering the flask with cotton wool to prevent air from contaminating it and shaking regularly to provide oxygen for the growing bacteria.
60
What does culturing microorganisms on agar gel plate include?
Making the plate:
- hot sterilised jelly is poured into a sterilised Petri dish, which is left to cool and set
- 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 (stored upside down)
61
Why do petri dishes and culture media have to be sterilised before use?
to avoid contamination, could be harmful or affect investigation.
62
Why do inoculating loops have to be sterilised by passing through a flame?
kills unwanted microorganisms.
63
Why does the petri dish have to be stored upside down?
prevent condensation from the lid landing on the agar surface and disrupting growth.
64
Why does the lid of the Petri dish need to be sealed with tape?
prevent contamination, harmful anaerobic bacteria could grow if fully sealed
65
Why should cultures not be incubated at temperatures higher than 25 degrees?
if higher temp, harmful bacteria could grow that would harm humans.
66
How do bacteria multiply?
binary fission (one splitting into two)
67
What is the equation for bacteria at end?
= bacteria at beginning x 2 to the power of number of divisions.
68
How to calculate the number of divisions?
divide the time the population is left by the mean division time for that bacteria
69
What does the investigation to test the effect of different antibiotics involve?
- soak paper discs in different types of antibiotics and place on 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
- if the bacteria are resistant to the antibiotic they will not die, but non-resistant will die, leaving and inhibition zone.
- leave the plate at 25 degrees for 2 days
- the zone of inhibition can be measured- the bigger it is, the more bacteria are killed and therefore the more effective the antibiotic is.
70
In growing bacteria and testing the effectiveness of antibiotics, you need to calculate cross-sectional areas (of colonies or inhibition zones) using what?
pie r squared.
71
What is found in the chromosomes?
coils of DNA
72
Where are chromosomes found?
nucleus
73
What is a gene?
a short section of DNA that codes for a protein and as a result controls a characteristic - therefore each chromosome carried many genes
74
How many chromosomes are there in each cell in the body?
23 pairs, 46.
75
What are gametes?
sex cells
76
How many chromosomes are there in each gamete?
23
77
What is the cell cycle?
a series of steps that the cell has to undergo in order to divide
78
What are the 3 stages in the cell cycle?
interphase, mitosis, cytokinesis
79
What is the interphase?
the cell grows, organelles increase in number, DNA is replicated and energy stores are increased.
80
What occurs during stage 2, mitosis?
chromosomes line up at the equator of the cell and cell fibres pull each chromosome to either side of the cell.
81
What occurs during the 3rd stage, cytokinesis?
two identical daughter cells form, cytoplasm and cell membrane divide.
82
Why is cell division by mitosis important?
growth and development and replacing damaged cells.
83
Where else is mitosis a vital part?
asecual reproduction
84
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.
85
What are the different types of stem cells?
embryonic, adult and meristem.
86
What are some qualities of embryonic stem cells?
forms when an egg and sperm cell fuse to form a zygote, differentiate into any type of cell in the body, scientists can clone these cells and direct them to differentiate into almost any cell in the body, potentially can be used to replace insulin-producing cell in those suffering from diabetes, new neural cells for diseases such as Alzheimer's or nerve cells for those paralysed with spinal cord injuries.
87
What are qualities of adult stem cells?
found in bone marrow they can form many types of cells including blood cells.
88
What are some qualities of meristems in plants?
found in root and shoot tips, differentiate into any type of plant and have this ability throughout the life, used to make clones to help disease resistance and extinction
89
What is therapeutic cloning?
involves and embryo being produced with the same genes as the patient.
90
What does therapeutic cloning include?
- the embryo being produced with same genes
- the embryo produced could then be harvested to obtain the embryonic stem cells
- these could be grown into any cells the patient needed, such as new tissues or organs
- the advantage is that they would not be rejected as they would have the exact same genetic make-up as the individual.
91
What are the 3 uses of stem cells?
therapeutic cloning, plant clones, and replace broken cells.
92
What are the benefits of research with stem cells?
- can be used to replace damaged or diseased body parts
- unwanted embryos from fertility clinics could be used as they would otherwise be discarded of
- research into the process of differentiation.
93
What are the disadvantages of research with stem cells?
- we do not completely understand the process of differentiation, so its hard to control stem cells to form the cells we desire
- removal of stem cells results in destruction of the embryo
- people may have religious or ethical objections
- can be contaminated, transferring a virus to the individual
- money and time could be better spent into other areas of medicine
94
What is diffusion?
the spreading out of the particles, resulting in a net movement from an area of higher concentration to an area of lower concentration.
95
What are some examples of molecules that are small enough to diffuse?
oxygen, glucose, amino acids, water,
96
Where are some examples of diffusion occuring in the body?
- gas exchange, oxygen moves through the membranes of alveoli into the red blood cells, and is carried to cells across the body for respiration, carbon dioxide moves from the red blood cells into the lungs to be exhaled
- excretion, urea moves from the liver cells into the blood plasma to be transported to the kidney
97
What are the factors that affect diffusion?
concentration gradient, temperature, surface area
98
How does the concentration gradient affect diffusion?
the greater the difference in concentration, the faster the rate of diffusion, this is because more particles are randomly moving down the gradient than are moving against it
99
How does temperature affect diffusion?
the greater the temperature, the greater the movement of particles, resulting in more collisions and therefore a faster rate of diffusion
100
How does the surface area of the membrane affect diffusion?
the greater the surface area, the more space for particles to move through, resulting in a faster rate of diffusion
101
How do you calculate surface area?
length x width
102
How do you calculate volume?
length x width x height
103
What adaptations do the lungs have to allow molecules to be transported in and out of cells?
in the lungs, oxygen is transferred to the blood and carbon dioxide is transferred to the lungs, this takes place across the surface of millions of air sacs called alveoli, which are covered in tiny capillaries, which supply the blood.
104
What adaptations does the small intestine have that allows molecules to be transported in and out of cells?
in the small intestine, cells have projections called villi, digested food is absorbed over the membrane of these cells, into the bloodstream
105
How are the gills adapted to allow the movement of molecules in and out?
the gills are where gas exchange takes place in fish, water which has oxygen passes through the mouth and over the gills, each gill has plates called gill filaments, adn 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.
106
How are the roots adapted for molecules to move in and out?
the roots of plants are adapted to take up water and mineral ions, roots have root hair cells with large surface areas, which project into the soil
107
How are the leaves adapted for molecules to move in and out?
in the leaves of the plant there are many different tissues to aid with gas exchange, carbon dioxide diffuses through stomata for photosynthesis, whilst oxygen and water vapour move out through them, the stomata are controlled by guard cells, which change the size of the stomata based on how much water the plant received (the guard cells swell with lots of water and make the stomata larger)
108
What adaptations are present for a more efficient diffusion pathway?
having a large surface area, having a thin membrane, having an efficient blood supply/being ventilated
109
How does having a large surface area affect diffusion?
the greater the surface area, the more particles can move through, resulting in a faster rate of diffusion
110
How does having a thin membrane affect diffusion?
provides a short diffusion pathway, allowing the process to occur faster
111
How does having an efficient blood supply/being ventilated affect diffusion?
creates a steep concentration gradient so diffusion occurs faster
112
What is osmosis?
the movement of water from a less concentrated solution to a more concentrated one through a partially permeable membrane, a dilute solution to a more concentrated, moves from an area of high water potential to low water potential down the concentration gradient, its passive
113
In animals, what occurs if the external solution is more dilute?
move into animal cells causing them to burst
114
In animals, what occurs when the external solution is more concentrated?
excess water will leave the cell causing it to become shrivelled.
115
What is an isotonic solution?
concentration of sugar in external solution is the same as internal, no movement.
116
What is a hypertonic solution?
concentration of sugar in external solution is higher than the internal, water moves out
117
What is a hypotonic solution?
concentration of sugar in external solution is lower than the internal, water moves in
118
In plants, what occurs when the external solution is more dilute?
water will move into the cell and into the vacuole, causing it to swell, resulting in pressure called turgor
119
In plants, what occurs if the external solution is less dilute?
water will move out of the cell and they will become soft, eventually the cell membrane will move away from the cell wall called plasmolysis and it will die.
120
What is active transport?
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, this is active
121
How does active transport occur 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
122
How does active transport occur 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 a lower concentration 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
