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Biology > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

features of eukaryotic cells

A

cell membrane
cytoplasm
nucleus containing dna

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2
Q

features of prokaryotic cells

A

smaller
cell wall
cell membrane
cytoplasm
single circular strand of DNA and plasmids

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3
Q

function of nucleus

A

contains dna coding for a particular protein needed to build cells

enclosed in a nuclear membrane

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4
Q

function of cytoplasm

A

liquid substance in which chemical reactions occur

contains enzymes

organelles are found in it

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5
Q

role of cell membrane

A

controls what enters and exits the cell

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6
Q

role of mitochondria

A

where aerobic respiration reactions occur, providing energy for the cell

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7
Q

role of ribosomes

A

where protein synthesis occurs

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8
Q

function of chloroplasts

A

where photosynthesis takes place, providing food for the plant

contains chlorophyll pigment which harvests the light needed for photosynthesis

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9
Q

function of permanent vacuole

A

contains cell sap

found within the cytoplasm

improves cells rigidity

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10
Q

function of cell wall

A

made from cellulose

provides strength to the cell

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11
Q

difference of cell wall in bacterial cells

A

made of a different compound

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12
Q

where are single circular strands of dna found in bacterial cells

A

float un the cytoplasm as have no nucleus

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13
Q

what are plasmids in bacterial cells

A

small rings of dna

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14
Q

what is differentiation?

A

a process that involves the cell gaining new sub cellular structures in order for it to be suited to its role

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15
Q

how often can stem cells differentiate

A

their whole life

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16
Q

how many times can cells differentiate in animals?

A

once

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17
Q

how many times can cells regenerate in plants?

A

retain the ability to regenerate whenever

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18
Q

what is the function of a sperm cell?

A

specialised to carry the males dna to the egg for successful reproduction

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19
Q

what adaptions do sperm cells have?

A

streamlined head and long tail
many mitochondria for energy for cell to move
acrosome has digestive enzymes which break down the outer layers of membrane of the egg cell

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20
Q

what is the function of nerve cells?

A

transmit electrical signals quickly from one place in the body to another

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21
Q

what are the adaptions of nerve cells

A

axon is long so impulses can be carried along long distances

lots of extensions from the cell body called dendrites meaning branches connections can form with other nerve cells

the nerve endings have many mitochondria which supply the nerve to make neurotransmitters

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22
Q

what is the function of muscle cells

A

specialised too contract quickly to move bones or squeeze therefore causing movement

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23
Q

what adaptations do muscle cells have

A

special proteins that slide over each other causing the muscle to contract

lots of mitochondria to provide energy from respiration for contraction
store glycogen which is used in respiration

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24
Q

what is the function of a root hair cell

A

specialised to take up water by osmosis and mineral ions by active transport from the soil

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25
Q

adaptations of root hair cells

A

large surface area from root hairs for more water to move in

large permanent vacuole affects the speed of movement for water from soil to the cell

mitochondria to provide energy for the active transport of mineral ions to the root hair cell

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26
Q

function of xylem cells

A

specialised to transport water and mineral ions up the plant from the roots to the shoots

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27
Q

adaptations of xylem cells

A

lignin causes the cells to die and become hollow to join end to end and form a tube of water for mineral ions to move through

lignin is deposited in spirals which helps the cells withstand the water pressure

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28
Q

what is the function of phloem cells

A

specialise dto carry the products of photosynthesis to all parts pf the plants

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29
Q

what is the adaptations of phloem cells

A

cell wall for sieve plates when they break down allowing substances to move from cell to cell

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30
Q

what do bacterial cells have instead of a nucleus?

A

single circular strand of DNA that floats freely in the cytoplasm

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31
Q

what are plasmids?

A

small rings of dna in a bacterial cell

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32
Q

magnification calculation

A

magnification = image size / real size

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33
Q

what do light microscopes do?

A

use light and lenses to form an image of a specimen and magnify it

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34
Q

what do light microscopes let you see?

A

individual cells and large sub cellular structures like nuclei

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35
Q

what do electron microscopes do?

A

use electrons to form an image with a higher magnification than light microscopes

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36
Q

what do electron microscopes let us see?

A

smaller things like internal structure of mitochondria and chloroplasts, ribosomes and plasmids due to the higher resolution

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37
Q

what is resolution

A

the ability to distinguish between two points

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38
Q

what is differentiation?

A

the process by which a cell changes to become specialised for its job

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39
Q

what happens as cells change to help them carry out new functions?

A

different subcellular structures developed

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40
Q

when does differentiation usually occur?

A

as an organism develops

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41
Q

when is the ability to differentiate lost in animal cells

A

early stage

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42
Q

when is the ability for plant cells to differentiate lost

A

never in most plants

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43
Q

what are the cells that differentiate in mature animals used for?

A

repairing and replacing cells such as skin and blood cells

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44
Q

what are undifferentiated cells called

A

stem cells

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45
Q

phloem and xylem cells adaptations

A

form tubes which transports food and water around plants
xylem cells hollow and phloem cells few subcellular structures for flow of movement

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46
Q

how do stem cells turn into different types of cell

A

divide to produce more undifferentiated cells
can differentiate from here depending on instructions given

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47
Q

where are stem cells found in humans?

A

embryos , bone marrow

48
Q

what can’t adult stem cells do?

A

can’t turn into any cell type but only certain ones such as blood cells

49
Q

what can stem cells be used for?

A

replacing fault cells in the body

50
Q

what happens in therapeutic cloning

A

embryo made to have the same genetic information as the patients to avoid rejection

51
Q

what is the risk of therapeutic cloning

A

contaminated with a virus from the lab

52
Q

why are people against stem cell research

A

potential human life should be cared for
concentrate on developing other sources of stem cells without embryo use

53
Q

why are people for stem cell research

A

patients who already exist are more important than embryo rights
usually embryo stem cells are unwanted ones from fertility clinics

54
Q

where are stem cells found in plants

A

meristems

55
Q

where are stem cells found

A

human embryos
adult bone marrow

56
Q

what is the difference between embryonic stem cells and bone marrow stem cells?

A

bone marrow stem cells can’t turn to any cell type

57
Q

how are stem cells used in medicine?

A

grown in a lab to produce genetically identical cells and made to differentiate into specialised cells

58
Q

what could embryonic stem cells be used for producing?

A

insulin producing cells
neural cells for diseases such as alzheimer’s
nerve cells for spinal cord injuries

59
Q

what is therapeutic cloning?

A

an embryo being produced with the same genes as the patient

60
Q

why does therapeutic cloning help stem cell use?

A

stops the patient rejecting them

61
Q

what is the risk of therapeutic cloning?

A

may become contaminated with a virus from the lab

62
Q

what are the benefits of stem cell research

A

can be used to replace damaged or diseased body parts
unwanted embryos from fertility clinics would have a use
researches into the process of differentiation

63
Q

problems with stem cell research (5)

A

hard to control stem cells to form the cells we desire
destroys the embryo
religious or ethical objections due to interference with natural process or reproduction
could catch a virus from the lab which would be transferred to the patient
money and time could be spent on other areas of medicine

64
Q

where are stem cells found in plants?

A

meristems ( found in roots and shoot tips)

65
Q

how are plant stem cells used

A

differentiate into any type of plant for its whole life
make clones of the plant quickly and cheaply
grow plants of rare species at risk of extinction
grow crops of plants with desirable features

66
Q

where is genetic information found?

A

chromosomes in the nucleus which contain coils of dna

67
Q

what does each chromosome carry

A

a large number of genes

68
Q

what are genes?

A

a short section of dna that codes for a protein and controls characteristics eg hair colour

69
Q

how many chromosomes are in body cells

A

23 pairs (one from mother one from father)

70
Q

how many chromosomes are in each cell?

A

46

71
Q

what cell is the exception for number of chromosomes?

A

sex cells (gametes) 23 chromosomes total in each cell

72
Q

what is the cell cycle?

A

a series of steps that the cell has to undergo in order to divide

73
Q

what is mitosis

A

a stage in the cell cycle when the cell divides

74
Q

what happens in the first main stage of the cell cycle

A

dna is spread out in long strings
the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes
duplicates its dna for one copy for each new cell. dna is copied and forms x shaped chromosomes and each arm is identical

75
Q

what happens during mitosis

A

chromosomes line up at the centre of the cell and cell fibres pull them apart , two arms go to opposite ends of the cell
membranes form around the sets of chromosomes and become the nucleus of the two new cells as the nucleus has divided
cytoplasm and cell membrane divide
cell has now produced two new daughter cells with the same dna , and same dna as parent cell

76
Q

what is cell division by mitosis for?

A

in multicellular organs for growth and development
replacing damaged cells
asexual reproduction

77
Q

what is binary fission?

A

the process of reproduction in prokaryotic cells

78
Q

what are the steps of binary fission

A

circular dna and plasmids replicate
cell gets bigger and circular dna strands move to opposite poles of the cell
cytoplasm begins to divide and new cell walls begin to form
cytoplasm divides and two daughter cells produced with one copy of the circular dna but a variable number of copies of the plasmids

79
Q

what speeds up bacterial division

A

warm environments , lots of nutrients

80
Q

what happens if conditions become unfavourable for bacterial cells division

A

cells will stop dividing and eventually begin to die

81
Q

what is diffusion

A

the spreading out of particles from an area of higher concentration to an area of lower concentration

82
Q

why is diffusion passive

A

No energy is required

83
Q

What does a molecule need to be to diffuse

A

Small

84
Q

Which molecules can diffuse

A

Glucose , amino acids , water

85
Q

How does oxygen diffuse in the body

A

Moves through membranes of alveoli into red blood cells
Carried to body cells for respiration

86
Q

How does carbon dioxide diffuse out of the body

A

Moves from red blood cells to the lungs to be exhaled

87
Q

What is the movement of oxygen into and carbon dioxide out of the lungs called

A

Gas exchange

88
Q

How does urea diffuse

A

Moves from the liver cells into blood plasma to be transported to the kidney for excretion

89
Q

Which factors affect the rate of diffusion

A

Concentration gradient
Temperature
Surface area of the molecule

90
Q

How does concentration gradient affect diffusion

A

Greater the difference in concentration , faster the rate of diffusion .
More particles are randomly moving down the gradient than are moving against it

91
Q

How does temperature affect the rate of diffusion

A

Greater the temperature , the greater the movement of particles resulting in more collisions and a faster rate

92
Q

How does surface area affect the rate of diffusion

A

Greater the surface the more space for particles to move through

93
Q

What is a surface area to volume ratio

A

The size of the surface area of the organism compared to its volume

94
Q

How do you calculate surface area to volume ratio

A

Volume x (length x width)
Write the ratio in smallest whole numbers

95
Q

What is the effect of a large sa to vol ratio

A

Less likely to require specialised exchange surfaces and a transport system

96
Q

How can single celled organisms use diffusion to transport molecules into their body from air

A

Have a large sa to vol ratio and have low metabolic demands so diffusion across the surface is sufficient to meet their needs

97
Q

Why do multicellular organisms need to have adaptations to increase cell movement in and out

A

Sa to vol ratio is small so cannot rely on diffusion alone

98
Q

What is an adaptation of alveoli to increase diffusion

A

Covered in tiny capillaries which supply blood

99
Q

What is the role of the villi for diffusion

A

Cell projections
Digested food is absorbed over the membrane of these cells into the bloodstream

100
Q

What is the role of gills in diffusion

A

Water with oxygen passes through mouth over the gills
Have gill filaments and gill lamellae where diffusion of oxygen into blood and diffusion of co2 into water happens
Blood flows in one direction and water flows in the other

101
Q

what is the adaptation of the roots of plants for diffusion

A

Root hair cells with large surface area
Project into soil and take up water and mineral ions

102
Q

What is the role of the stomata in diffusion of leaves

A

Carbon dioxide diffuses through
Oxygen and water vapour move out

103
Q

How does having a thin membrane affect diffusion

A

Short diffusion pathway

104
Q

How does having an efficient blood supply or being ventilated affect diffusion

A

Steep concentration gradient

105
Q

What is osmosis

A

The movement of water from a less concentrated solution to a more concentrated one through a partially permeable membrane

106
Q

What kind of concentration of water does a dilute sugar solution have

A

High and a high water potential

107
Q

What does the cytoplasm contain that affects osmosis

A

Contains salts and sugars
When a cell is placed in a dilute solution water will move in

108
Q

What is an isotonic solution

A

When the concentration of sugar in external solution is the same as the internal and there is no movement

109
Q

What is a hypertonic solution

A

If the concentration of the sugar in external solution is higher than the internal , water moves out

110
Q

What is a hypotonic solution

A

If the concentration of sugar in external solution is lower than the internal , water moves in

111
Q

What happens in animal cells if the external solution is more dilute

A

It will swell up and burst

112
Q

What happens to animal cells if the external solution is more concentrated

A

Excess water will leave the cell causing it to become shrivelled

113
Q

What happens in plant cells if the external solution is more dilute

A

Water will move into the cell and the vacuole causing it to swell and resulting in pressure called turgor

114
Q

What happens in plant cells if the external solution is less dilute

A

Water will move out of the cell
Cell becomes soft
Cell membrane will move away from the cell wall (plasmolysis) and will die

115
Q

What is active transport

A

Movement of particles from an area where they are in lower concentration to an area in higher concentration against a concentration gradient using energy from respiration

116
Q

How does active transport work in root hairs

A

Take up water and mineral ions from soil
Mineral ions Usually in higher concentration in the cells meaning diffusion cannot take place
Requires energy from respiration

117
Q

How does active transport work in the gut

A

Substances such as glucose and amino acids from food move from gut to bloodstream
Lower concentration of sugar in the gut than blood so active transport required to move sugar to the blood against its concentration gradient

Biology (22 decks)

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