cell biology (T1) Flashcards
1
Q
what are eukaryotic cells? give examples.
A
a more complex cell that has a nucleus. e.g. animal and plant cell
2
Q
what are prokaryotic cells? give examples.
A
a simple cell without a nucleus. e.g. bacteria
3
Q
where is the genetic material in eukaryotic and prokaryotic cells?
A
in eukaryotes it is enclosed in the nucleus, in prokaryotes it is a small loop of DNA and in plasmids.
4
Q
what is the prokaryotic cell wall composed of?
A
Peptidoglycan
5
Q
what are plasmids
A
small circular loops of dna found free in the cytoplasm and seperate from main dna. they carry genes that provide genetic advantages e.g. antibiotic resistance.
6
Q
what is order of magnitude?
A
a power to the base of 10 used to quantify and compare size e.g. 10^2 is 1 order of magnitude bigger than 10^1.
7
Q
what is a cm, mm, µm, nm
A
1 x 10 ^-2m, 1 x 10^-3 m, 1 x 10^-6, 1 x 10^-9
8
Q
list the components of both plant and animal cells
A
cell membrane, mitochondria, cytoplasm, ribosomes, nucleus
9
Q
list the additional components found in plant cells
A
permanent vacuole, chloroplast, cell wall
10
Q
other than storing genetic information, what is the function of the nucleus
A
controls cellular activities
11
Q
describe the structure of cytoplasm
A
- fluid component of cell
- contains organelles, enzymes and dissolved ions and nutrients
12
Q
what is the function of cytoplasm
A
site of cellular reactions
13
Q
what is the function of the cell membrane
A
controls what goes in and out of the cell
14
Q
what is the function of mitochondria
A
site of aerobic respiration
15
Q
what is the function of the ribosome
A
site of protein synthesis
16
Q
what is the plant cell wall made of
A
cellulose
17
Q
what is the function of the plant cell wall
A
provides strength
18
Q
what does the permanent vacuole contain
A
cell sap
19
Q
what is the function of the permanent vacuole
A
supports the cell
20
Q
what is the function of chloroplasts
A
site of photosynthesis
21
Q
describe how sperm cells in animals are adapted to their function
A
- (haploid) nucleus contains genetic information of father
- tail enables movement
- mitochondria provides energy for the cell
- acrosome contains enzymes that digest the egg cell membrane
22
Q
describe how nerve cells are adapted to their function
A
- long axon allows electrical impulses to be transmitted all over the body
- dendrites from the cell body connect to and receive impulses from other nerve cells, muscles and glands
- myelin sheath insulates the axon and speeds up the transmission of impulses along the nerve cell
23
Q
describe how muscle cells are adapted to their function
A
- arrangement of protein filaments allow them to slide over each other to produce muscle contraction
- mitochondria to provide energy for muscle contraction
24
Q
describe how root hair cells are adapted to their function
A
- large surface area to absorb nutrients and water from surrounding soil
- thin walls that do not restrict water absorption
25
describe how xylem cells are adapted to their function
- no end walls to provide a continuous route for water to flow
26
describe how phloem cells are adapted to their functions
- sieve plates let dissolved amino acids and sugar to be transported up and down the stem
- companion cells provide energy needed for active transport of substances along the phloem
27
what is cell differentiation
the process by which cells become specialised
28
why is differentiation important
allows production of different tissues and organs that perform various vital functions in the human body
29
at what point in their life cycle to most animal cells differentiate
early in their life cycle
30
for how long do plant cells retain their ability to differentiate
throughout their life
31
what is the purpose of cell division in mature animals
repair and replacement of cells
32
what changes does a cell go through as it differentiates
becomes specialised by developing different sub-cellular structures to enable it to perform a specific function
33
define magnification
the number of times bigger an image appears compared to the actual size of the real object
34
define resolution
the smallest distance between two objects that can still be distinguished
35
how does a light microscope work
passes a beam of light through a specimen which travels through the eyepiece lens allowing the specimen to be observed
36
what are advantages of light microscopes (4)
- inexpensive
- easy to use
- portable
-can observe both live and dead specimens
37
what are disadvantages of light microscopes
- limited resolution
- lower magnification than electron microscopes
38
how does an electron microscope work
uses electron beams which are focused by magnets the electrons hit a fluorescent screen which emit visible light producing an image
39
what are advantages of electron microscopes
- greater magnification
- greater resolution
40
why do electron microscopes have a higher magnification and resolution
they use a beam of electrons with a shorter wavelength than light
41
what are disadvantages of electron microscopes
- expensive
- hard to use
- not portable
-can only see dead specimens
42
magnification equation
magnification= image size ÷ real size
43
how many chromosome are found in human body cells
46
44
how many chromosomes are found in gametes
23
45
how are chromosomes arranged in the nucleus of a human body cells
46 chromosomes form 23 pairs
46
what are the three main stages of the cell cycle
- chromosomes duplicate
- mitosis
-cell divides
47
why is mitosis important
- produces identical cells that all have the same genetic information
- produces additional cells for growth and repair
48
describe the first stage of the cell cycle
cells grow, replicate dna and synthesise more organelles
49
describe the second stage of the cell cycle
each chromosome in a pair is pulled to opposite poles of the cell then the nucleus divides
50
describe the third stage of the cell cycle
the cytoplasm and cell membrane split, two daughter cells are provided
51
what is a stem cell
unspecialised cell capable of differentiating into other cell types
52
what is the function of stem cells in embryos
embryonic stem cells can differentiate into any type of cell and they can be used to treat conditions such as paralysis and diabetes
53
what is the function of the stem cells in bone marrow
adult stem cells can differentiate into several cell types to replace dead or damaged tissues, bone marrow turns into many types of blood cell
54
what is the function of stem cells in plant meristems
to differentiate into any type of cell required by the plant
55
what is therapeutic cloning
cloning method where an embryo is produced with the same genetic makeup as the patient. the stem cells which originate from the embryo will not be rejected by the patients immune system so can be used to treat certain medical conditions
56
what are advantages of cloning plants using meristem stem cells
- can prevent rare plants from becoming extinct
- can produce large number of plants with a favourable characteristic
- can produce identical plants for research
57
what are issues associated with the use of stem cells
- many embryonic stem cells are sourced from aborted embryos -> some people have an ethical/ religious objection
- development of stem cell therapies is slow, difficult and expensive.
- adult stem cells with viruses could transfer infections to the patient
- if donor cells do not have a similar genetic makeup to the patient, an immune response could be triggered
58
what is diffusion
the net movement of particles from an area of high concentration to an area of low concentration
59
what three main factors affect the rate of diffusion
- surface area
- concentration gradient
- temperature
60
give examples of substances transported by diffusion in the lungs and kidney
- lungs: oxygen diffuses into the blood from the lungs and carbon dioxide diffuses into the lungs from the blood
- kidney: urea diffuses from the cells into blood plasma so it can be excreted in urine
61
how are single-celled organisms adapted for diffusion
large surface area:volume ratio - maximises the rate of diffusion
62
what four factors increase the effectiveness of a gas exchange surface
- good blood supply
- large surface area
- thin walls
- ventilation
63
what is osmosis
the movement of water molecules from an area with a high concentration of water to an area of low water concentration through a partially permeable membrane
64
what is meant when a solution is isotonic to a cell
the water concentration of the solution and the cell is the same
65
what is meant when a solution is hypertonic to a cell
the water concentration of the solution is lower (higher solute concentration) than the cell
66
what is meant when a solution is hypotonic to a cell
the water concentration of the solution is higher (lower solute concentration)
67
what will happen to an animal cell in a very hypotonic solution
water will move into the cell until it bursts
68
what will happen to an animal cell in a very hypertonic solution
water will leave the cell causing it to shrivel up
69
how do plant leaves and stems remain rigid
water moves in by osmosis causing the vacuole to swell and the cytoplasm to press against the cell wall
70
what may happen when a plant cell is places in a very hypertonic solution
water moves out of the cell by osmosis causing the vacuole and cytoplasm to decrease in size. the cell membrane may pull away from the cell wall.
71
what is active transport
the movement of molecules from an area of low concentration to an area of high concentration against the concentration gradient, using energy from respiration
72
how do root hair cells use active transport
take up mineral ions from a lower concentration in soil, ions such as magnesium and nitrate are needed for healthy growth
73
how is active transport used to absorb the products of digestion
active transport is used to transport glucose from a low concentration to a higher concentration in the blood - glucose is then transported into tissues to be used in respiration.
