cell biology Flashcards
1
Q
name the two types of microscopes
A
light and electron
2
Q
how do light microscopes work?
A
they use a beam of light to form an image of an object
3
Q
what are the pros of using light microscopes?
A
relatively cheap
can be used almost everywhere
can magnify live specimen
4
Q
what are the cons of using light microscopes?
A
resolution isn’t high enough to see some sub-cellular organelles like like mitochondria and ribosomes
magnification of only x2000
5
Q
how do electron microscopes work?
A
they use a beam of electrons to form an image
6
Q
what are the pros of using electron microscopes?
A
very high magnification (x2000000)
high resolution and can see mitochondria and ribosomes
7
Q
what is a scanning electron microscope?
A
they give 3D images but have lower magnification
8
Q
magnification
A
how much bigger an object is made
9
Q
resolution
A
ability to distinguish two separate points from each other
10
Q
resolving power
A
how much detail the microscope can show
11
Q
give examples of prokaryotic cells
A
bacteria like e.coli and archaea
12
Q
what are the properties of eukaryotic cells?
A
nuclear membrane surrounding genetic material
numerous membrane-bound organelles
complex internal structure
can be single or multi cellular
13
Q
what are the properties of prokaryotic cells?
A
no nuclear membrane
no membrane bound organelles
simple structure
contains rings of DNA called plasmids
14
Q
similarities between eukaryotic and prokaryotic cells
A
DNA cytoplasm ribosomes cell membrane both can be unicellular both can have cilia and flagella
15
Q
what is the purpose of plasmids?
A
they are rings of DNA which transfer genetic material from one cell to another
16
Q
what is a flagella and what does it do?
A
it is a long strand of protein that lashes around and helps the bacterium move around
17
Q
how big is an average animal cell?
A
10-30 micrometres
18
Q
nucleus
A
controls the activities of the cell and holds the genetic material which is needed to repair or make new cells
19
Q
cytoplasm
A
a liquid gel in which the organelles are suspended in and where most of the chemical reactions occur
20
Q
cell membrane
A
controls what goes in and out of the cell such as glucose, minerals and hormones
21
Q
mitochondria
A
where aerobic respiration takes place which releases energy for the cell to use
22
Q
ribosomes
A
where proteins are synthesised
23
Q
what is the average size of a plant cell?
A
10-100 micrometres
24
Q
cell wall
A
made of cellulose that strengthens the cell and keeps it rigid
25
chloroplasts
contain a green substance called chlorophyll which is need in photosynthesis
26
vacuole
a space in the cytoplasm filled with cell sap which provides the cell with nutrients and keeps the cell rigid to support the plant
27
why where algae classified as plants for centuries?
they have similar features to plant cells and make their own food by photosynthesis but are now classified as protista
28
differentiation
process in which a cell changes from one cell type to another
29
specialisation
the structural adaptation of cells for a particular
| function
30
what is the function of nerve cells?
they carry electrical impulses around the body and to the brain
31
how are nerve cells adapted to their function?
lots of dendrites to make connections to other nerve cells
long axon to carry nerve impulses from one place to another
the nerve ending (known as synapses) are adapted to pass impulses using special transmitter chemicals and contain lots of mitochondria to provide energy to make these chemicals
the axon is insulated by a fatty myelin which increases the speed of the nerve impulses along the neuron
32
what is the function of a muscle cell?
they contract and relax to move bones, pump blood and aid digestion
33
how are striated muscle cells adapted to their function?
contain special proteins that slide over each other making the fibres contract
contain many mitochondria to transfer energy needed for the cells to contract and relax
store glycogen which can be broken down to glucose and used in cellular respiration
34
what is the function of sperm cells?
sperms cell fertilise a females egg and need to move through the female reproductive system to get to it
35
how are sperm cells adapted to their function?
long tail which helps the sperm cell move
the middle section of a sperm cell is filled with mitochondria which transfer energy needed for the tail to work
acrosomes stores enzymes for breaking down the outer layers of the egg
36
what is the function of root hair cells?
they absorb water and mineral ions
37
how are root hair cells adapted to their function?
large surface area for water to move into the cell
large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair
have many mitochondria that transfer energy needed for active transport
38
what is the function of photosynthetic cells?
photosynthetic cells are needed to carry out photosynthesis so the plant can make food
39
how are photosynthetic cells adapted to their function?
contain chloroplast
positioned in the leaf and outer layers of the stem so they can absorb as much light as possible
large vacuole that keeps the cell rigid which therefore supports the stem and keeps the leaf spread out for a large surface area
40
what is the function of xylem cells?
carry water and mineral ions from the root to the leaves and shoots
41
how are xylem cells adapted to their function?
lignin builds up in spirals in the cell walls which then die and form long hollow tubes which allow easy movement of water
lignin strengthens the walls which allows them to withstand the pressure of moving water
42
what is the function of phloem cells?
phloem carries food made by photosynthesis around the plant
43
how are phloem cells adapted to their function?
the cell wall between cells break down to form sieve plates which allow water carrying food to move freely
phloem cells are supported by companion cells that help keep them alive
44
diffusion
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 until they are in equilibrium
45
what affects the rate of diffusion?
steepness of the concentration gradient
temperature
surface area of the site of diffusion
46
give some examples of diffusion in the human body
simple sugars like glucose diffusing into blood and muscles
oxygen and carbon dioxide diffusing in and out of the lungs and blood during gas exchange
the waste product urea from cells into the blood plasma for excretion in the kidney
47
why do single-celled organism not need a transport system?
they have a large surface area to volume ratio and all cells are exposed to the environment so there is an effective exchange surface for diffusion
48
how is oxygen transported into our body cells?
oxygen from our lungs goes down the concentration gradient and diffuses into our red blood cells which travel around our body and the oxygen then moves into our body cells
49
how are surfaces and organs specialised for exchanging materials?
large surface area
thin membrane
efficient blood supple
good ventilation
50
osmosis
the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane
51
what does the cytoplasm contain?
the cytoplasm is made up of chemicals dissolved in water can contains a fairly concentrated solution of salts and sugars
52
how do water molecules move in osmosis?
they move from a dilute solution (which has a lot on water molecules) to a concentrated solution (which has few water molecules)
53
what should the concentration of solutes be like in your body?
the concentration of solutes needs to stay at the same level for your body cells to work properly
54
isotonic
when the concentration of the solution outside the cell is the same as the internal concentration of the cell
55
hypertonic
when the concentration of the solution outside the cell is greater than the internal concentration of the cell
(water moves out of the cell)
56
hypotonic
when the concentration of the solution outside the cell is lower than the internal concentration of the cell
(water moves into the cell)
57
why is maintaining equal concentration important in for animal cells?
if it is hypotonic too much water can move into the cell causing it to swell and burst
if it is hypertonic too much water can move out of the cell causing it to shrink and become shrivelled
58
what happens to plant cells when they are hypotonic?
water moves into the cell through osmosis which causes the vacuole to swell and push the cytoplasm against the cell membrane and the pressure will build up until no more water can enter the cell
59
what is this pressure called?
turgor
60
why do plants need the surrounding fluid to always be hypotonic
if it becomes isotonic or hypertonic water will leave the cell and it will become flaccid as there is no pressure on the cell walls causing the plant to wilt
61
what is plasmolysis?
when the plant cell loses water through osmosis the vacuole and cytoplasm shrink and the cytoplasm pulls away from the cell wall
62
active transport
when substances from a more dilute solution to a more concentrated solution (against a concentration gradient) which requires energy from respiration
63
when is active transport needed?
cells need to move substances in and out of their cells from a low concentration to a high concentration
64
give examples of when active transport is used?
mineral ions moving into root hair cells
sugar is actively absorbed out of your gut and kidneys and into your blood
glucose need for respiration
65
chromosomes
carry the genes that contains information needed for making new cells
66
genes
section of DNA that controls particular characteristics
67
DNA
long molecule that carries genetic information
68
how many chromosomes are there in the nucleus of our body cells?
46
69
how many chromosomes do gametes have?
23
70
what is mitosis
a type of cell division which produces two identical daughter cells
71
when is mitosis used/needed
development of new cells
growth
repair damaged cells
72
what happens in stage 1 of the cell cycle
the cells grow bigger, increase their mass, increase amount of ribosomes and mitochondria and they duplicate to form two copies of their DNA
73
what happens in stage 2 of the cell cycle
cell fibres form
chromosomes line up and the cell fibres attach themselves onto each half of the chromosome pairs
cell fibres shorten which separates the chromosomes and pulls them to each end of the dividing cell
74
what happens in stage 3 of the cell cycle
each set of chromosomes transfers into a nucleus and the cytoplasm divides forming two daughter cells
75
cytokinesis
the physical devision of the cytoplasm in mitosis
76
diploid
cells with two sets of chromosomes
77
haploids
cells with one set of chromosomes
78
homologous pair
a set of one maternal and one paternal chromosome
79
what is binary fission
the process by which prokaryotic organisms divide and reproduce
80
how does binary fission happen
- the large circular piece of DNA which contains the important genes is replicated
- plasmids also replicated
- the cell grows
- the two large circular strands move to opposite poles and the plasmids move randomly
- the cytoplasm spilts creating two separate cells
- the new cells create their own cell wall and membrane
81
in which conditions do bacteria grow fast in
warm, moist and with plenty of nutrients
82
what is a stem cell
an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation
83
what is an embryonic stem cell
- the cells that make up an embryo
| - can differentiate into any type of cell
84
what is the difference between adult and embryonic stem cells
unlike embryonic stem cells, adult stem cells cannot differentiate into any type of cell
85
where can adult stem cells be found
in bone marrow, these stem cells can form many types of cells including blood cells
86
where are plant stem cells found
in plant tissues called meristems which are found in areas of the plant that are continuously growing, like the tips of the roots and shoots
87
which tissues can plant stem cells differentiate
the can differentiate into any plant tissues
88
how long can plant cells differentiate for
the plants entire life
89
what is different about sperm and egg cells compared to other body cells
they only contain half the genetic material of a normal cell so that once they combine they will have the normal amount of DNA
90
what is differentiation
the process by which cells become specialised for their role
91
how can you clone plants
by using a cutting of the meristems to grow clones quickly and cheaply
92
why would you clone a plant
- to replicate rare species to reduce extinction
| - grow identical crops with desirable characteristics
93
how can human cells be cloned
by isolating either embryonic or adult stem cells and cloning them in a laboratory
94
what would cloned stem cells be used for
to replace any damaged cell in the body, like faulty blood cells
95
what is the problem with human stem cell cloning
patients body may recognise them as foreign and rejected
96
what is therapeutic cloning
when an embryo is made to have the same genetic material as the patient
97
what are the ethical issues with embryonic stem cell cloning
some people believe that it is wrong as the embryo has the potential for human life
98
what is the basic idea behind stem cells in medicine
to replace faulty cells with working stem cells
99
how would an embryonic stem cell be used to help cure diseases
- extract them from early embryos
- grow them in a lab
- stimulate them to differentiate into whichever type of specialised cell that we want
- give them to the patient to replace their faulty cells
100
what are the disadvantages of using embryonic stem cells
1. requires embryonic stem cells
| 2. could be rejected
101
what is an alternate to using embryonic stem cells to cure patients
using adult stem cells taken from the patient, there wouldn't be any rejection but adult stem cells can only differentiate into different types of blood cells
102
what are the 2 risks of using stem cells in medicine in general
1. virus transmission
| 2. tumour development
