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cells and immunity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does the nucleus do in a cell

A

contains genetic information needed for protein production and controls cell activities

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2
Q

what is chromatin made from and what does it form

A

a complex of DNA and histones that forms chromosomes

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3
Q

what does the nucleolus do

A

makes RNA which is made into ribosomes and moved out of the nucleus to the RER

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4
Q

what does the nuclear envelope do

A

double membrane which has nuclear pores to let relatively large molecules pass through

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5
Q

what is the structure and role of mitochondria

A

energy releasing cell

surrounded by a double membrane and the inner layers fold inwards to from cristae which projects into the matrix

the matrix contains enzymes needed for aerobic respiration.

there is also mitochondrial DNA and ribosomes in the matrix

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6
Q

what is the structure and role of the RER

A

consists of flattened membrane and they are studded with ribosomes.

it folds and processes proteins that have been made at the ribosomes

some of the proteins get secreted and some get put back onto the cell surface of the RER

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7
Q

what is the structure and role of the SER

A

consists of flattened membrane

synthesises and packages lipids

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8
Q

what is the structure an role of ribosomes

A

tiny organelles which can be found free in the cytoplasm or bound to the RER

consists of 2 subunits

is the site where proteins are made

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9
Q

what is the structure and role of the golgi apparatus

A

sack of fluid filled membrane bound flattened sacks

processes and packages new lipids and proteins also makes lysosomes

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10
Q

what is the role of Golgi vesicles

A

store lipids and proteins and transports them out of the cell`

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11
Q

what is the structure and role of lysosomes

A

spherical sacs surrounded by a single membrane

the Golgi vesicle contains digestive enzymes which digest cells and break down worn out cell components

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12
Q

what is the structure and role of centrioles

A

self-replicating organelles made up of microtubules and are only found in animal cells

they help organise cell division

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13
Q

what is the structure and role of microtubules

A

make up the cytoskeleton and are made up of tubulin o help provide support and movement of the cell

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14
Q

what are the structure and role of microvilli

A

cell membrane projections to increase the surface area for absorption

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15
Q

what is the structure and role of cilia

A

hair like projections made from microtubules to allow movement of substances over the cell surface

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16
Q

what is the structure and role of flagella

A

essential for the locomotion of individual organisms and are made of long microtubules

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17
Q

what is the structure and role of chloroplasts

A

small flattened scks surrounded by a double membrane

filled with liquid called stroma which contains sacks of thylakoid membranes containing chlorophyll called grana which are linked together by lamellae

photosynthesis happens in the grana and stroma

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18
Q

what is the structure and role of a vacuole

A

consist of a membrane called tonoplast filled with cell sap

maintains the pressure of the cell and keeps it rigid

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19
Q

what is the structure (in plants, fungi) and role of a cell wall how does it help with the transport of substances

A

in plants and algae - made of cellulose

in fungi it is made of chitin

provides structural support to help maintain the shape of the cell

there are pores within the cell wall called plasmodesmata which connects two cells together by their cytoplasm enabling the exchange and transport of substances

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20
Q

what is the role and structure of the plasma membrane

A

regulates movement of substances into and out of a cell

has receptor molecules allowing it to respond to chemical messengers and is made of a phospholipid bilayer

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21
Q

how is a red blood cell adapted for its function

A

they have a biconcave shape and do not contain a nucleus so there is as much space to transport oxygen as possible

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22
Q

how are neurons adapted for their function

A

have extensions called dendrites which allow communication with other neurons and a myelin sheath to insulate and speed up communication

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23
Q

how is a sperm cell adapted for its function

A

have the nucleus in the head containing half the normal number of chromosomes

has an enzyme called acrosome which is a digestive enzyme and helps break down the outer layer f the egg cell for fertilisation

has lots of mitochondria for movement

sometimes has a flagella to help with the locomotion of the cell

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24
Q

how are root hair cells adapted for their function

A

have thin walls so osmosis can happen quicker

mitochondria for active transport

a permanent vacuole to maintain the water potential of the cell

has a large surface area to increase absorption

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25
Q

how are xylem adapted for its function

A

have thickened outer walls strengthened with a substances called lignin

cells making up the xylem are virtually dead so water is allowed to flow freely

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26
Q

how are phloem adapted for their function

A

have very few subcellular structures allowing substances to flow easily

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27
Q

what is a tissue

A

a group of cells that work together to perform a particular function

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28
Q

what are the organelles a prokaryote has and what don’t they have

A

they have :
cytoplasm
ribosomes
cell wall
plasmids
capsules
flagellum

they dont have:
nucleus
membrane bound organelles

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29
Q

compare and contrast prokaryotic and eukaryotic cells

A

prokaryotic is smaller than eukaryotic

prokaryotic reproduces by binary fission and eukaryotic reproduces by mitosis or meiosis

DNA in prokaryotic is circular but in eukaryotic its linear

DNA in prokaryotic isn’t associated with histones but in eukaryotic it is

prokaryotic has no membrane bound organelles whereas eukaryotic has numerous types of membrane bound organelles

in prokaryotic the cell wall is made of murein in eukaryotic it is chitin or cellulose

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30
Q

what are the four structures of a virus

A

a nucleic acid core

a protein coat called a CAPSID

an envelope formed from the membrane of the host cell

attatchment proteins

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31
Q

what is magnification

A

how many times bigger the image is compared to the object

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32
Q

what is resolution

A

the ability to distinguish between 2 points

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33
Q

what conditions are needed for an electron microscope

A

vacuum

specimens are dead

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34
Q

what conditions are needed for a light microscope

A

no vacuum needed

specimens can be living or dead

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35
Q

compare and contrast electron and light microscopes

A

electron microscope
1. large and can b moved
2. vaccum needed
3. complicated sample prep
4. over 500,000 mag
5. 0.5 micrometers resolution
6. specimens are dead
7. uses electrons

light microscope
1. small and easy to move
2. no vacuum needed
3. easy sample prep
4. up to 2000 mag
5. 200 micrometers of resol.
6. specimens can be living or dead
7. uses light waves with long wavelength

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36
Q

what is an artifact

A

appear on the micrograph but aren’t part of the actual specimen normally are bubbles or dust.

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37
Q

compare and contrast TEM and SEM

A

TEM:
1. uses an electron gun to produce a beam that is focused onto the sample by an electromagnet
2. specimen needs to be as thin as possible so beam can pass through
3. gives resolution of up to 0.1 nanometers

SEM:
1. scans a beam of electrons across the surface of the spec. and electrons are scattered and gathered at the cathode ray tube
2. doesn’t need to be a thin sample as electrons are scattered by the specimen
3.can build up a 3D image by a computer
4. has a resolving power of around 20 nanometres

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38
Q

what is the equation for magnification

A

magnification= image size / actual size

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39
Q

what are the 3 steps in cell fractionation

A
  1. homogenisation
  2. filtration
  3. ultracentrifugation
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40
Q

describe homogenisation in cell fractionation

A

grinding the cells in a blender to break up the plasma membrane in a homogeniser and release organelles

the solution must be:
1. isotonic to prevent osmosis bursting cells
2. ice cold to reduce activity of enzymes that break down organelles
3. buffered to maintain pH o stop the denaturing of enzymes and proteins

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41
Q

describe filtration in cell fractionation

A

homogenised cell solution is filtered through a gauze to separate any large cell debris

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42
Q

describe ultracentrifugation in cell fractionation

A

cell fragments are poured into a tube and it is spun at a low speed and the heaviest organelles collect as a sediment and the supernatant is drained off and poured into another tube and spun at a higher speed and repeat

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43
Q

what is the usual order in cell fractionation or organelles

A
  1. nuclei
  2. mitochondria
    3.chloroplast
  3. lysosomes
  4. RER and SER
  5. ribosomes
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44
Q

what is the order of stages in mitosis

A
  1. interphase
  2. prophase
    3.metaphas
    4.anaphase
  3. telophase
  4. cytokinesis
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45
Q

what happens in interphase

A

G1 phase cells makes RNA and enzymes and other proteins ad receives signal to divide

S phase when the DNA replicates

G2 phase is when the cell continues to grow and the new DNA that has been synthesised is checked and errors are usually repaired

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46
Q

what happens in prophase

A
  1. chromosomes condense and become visible
  2. sister chromatids are joined together at the centromere
  3. the two centrosomes move towards opposite poles
  4. spindle fibers begin to emerge from the centrosomes
  5. nuclear envelope breaks down
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47
Q

what happens in metaphase

A
  1. centrosome reach opposite poles
  2. spindle fibres continue to extend from centrosome
  3. chromosomes are lined up at the equator of the spindle s they are equidistant to the two centrosomes pole
  4. spindle fibre reach the chromosomes are attach to the centromeres
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48
Q

what happens in anaphase

A
  1. sister chromatids separate at the centromere
  2. spindle fibres begin to shorten
  3. the seperated sister chromatides are pulled to opposite poles by the spindle fibres
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49
Q

what happens in telophase

A
  1. chromosomes arrive at opposite poles and begin to decondense
  2. nuclear envelopes begin reform around each set of chromosomes the spindle fibres break down
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50
Q

what happens in cytokenesis

A
  1. cytoplasm divides forming two genetically identical cells
  2. in animals cleavage forms and separated the daughter cells in plants the cell plate forms at the site of the metaphase plate and the new daughters cells are separated
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51
Q

what causes cancer

A

cancer arises due to uncontrolled mitosis and cancerous cells dividing repeatedly and uncontrollably when a change in the genes occurs to from an oncogene

52
Q

what are carcinogens

A

environmental agents that increase the chance of cancer

53
Q

what are treatments of cancer

A

anything that slows the rate of mitosis in cancerous cells down like chemotherapy

54
Q

what happens in binary fission and what is the final result

A
  1. single circular DNA undergoes DNA replication
  2. any plasmids present undergo DNA replication
  3. the parent cell divides into two cells with the cytoplasm roughly halved between the two
  4. the two daughter cells contains one copy of the circular DNA molecule and a variable number of plasmids
55
Q

what happens in viral replication

A
  1. virus attachment proteins bind to complementary receptor proteins on host cell surface membrane
  2. the virus injects its DNA or RNA into the host cell
  3. the host cell uses the nucleic acid and ribosomes from the virus to produce new viral proteins
  4. host cell bursts open and releases the new viral proteins and takes a section of the membrane with it to create an envelope
56
Q

why is the phospholipid bilayers described as fluid mosaic

A

fluid- proteins can move around and phospholipids mainly move sideways within their own layers

mosaic- the scattered pattern produced by proteins within the phospholipid bilayer

57
Q

what happens if you mix phospholipids with water

A

they from spheres with the hydrophobic tails pointing inwards and the hydrophilic heads facing out called a micelle

58
Q

describe the structure of a phospholipid membrane

A

hydrophobic tails point inwards
hydrophilic heads point inwards

individual phospholipids move by diffusion

59
Q

what is the role of the phospholipid bilayer

A

act as a barrier to water soluble substances and ensure that they cant leak out of the cell as well

60
Q

what is the role of cholesterol in the membrane

A

regulate the fluidity of the membrane and contribute to the impermeability of the membrane and increase its strength and stability

they also prevent the membrane from fractioning in low temperatures and bid with the phospholipids in high temperatures to stabilise the cell membrane and stopping it becoming too fluid

61
Q

where are cholesterol found in a cell and what type of cell

A

in between phospholipids and only in eukaryotes

62
Q

what do glycolipids and glycoproteins do in the cell membrane

A

act as receptor sites allowing them to bind to certain substances

they also help with adhesion and stabilization and and act as signaling receptors for hormones and neurotransmitters

some act as cell markers or antigens from cell to cell recognition

63
Q

what do transport proteins do in the cell surface membrane and why is it important

A

they allow substances like ions and polar molecules to travel through the membrane as they cant get through the phospholipid bilayer

64
Q

what is diffusion

A

diffusion is the net movement of a substance from a region of its higher concentration to a region of lower concentration

65
Q

what four factors effect the rate of diffusion

A

concentration gradient

temperature

surface area

properties of molecules or ions

66
Q

what is facilitated diffusion for

A

it allows substances hat cant diffuse through the phospholipid bilayer of cell membranes cross

67
Q

what is the structure of a channel protein and what does this allow to happen

A

has hydrophillic and hydrophobic amino acids that fold over to form a channel that is water filled allowing charged substances through by facilitated diffusion

68
Q

what is the structure of a carrier protein and what does it do in order to perform its function

A

they switch shapes to let substances pass as the binding site to be open on one side of the protein at a time

it opens to let the substance through one end and then shuts that end and opens the other end to let it through again

69
Q

what is the definition of osmosis

A

the diffusion of water particles from a dilute solution to a more concentrated solution across a semi permeable membrane

70
Q

what happens if a plant is put in a pure or dilute solution of water

A
  1. water will enter the plant cell through its partially permeable membrane by osmosis
71
Q

what happens if a plant is placed in a solution with lower water potential then the plant cell water

A

1.the plant cell water will leave the plant cell through its partially permeable membrane by osmosis

2.As water leaves the vacuole of the plant cell the volume of the plant cell decreases

3.The protoplast gradually shrinks and no longer exerts pressure on the cell wall and as it continues to shrink it begins to pull away from the cell wall and this is known as plasmolysis.

72
Q

what happens if an animal cell is placed in a solution with lower water potential than the cell

A

cell water will leave the cell through its partially permeable membrane by osmosis and the cell will shrink and shrivel up this occurs in a hypertonic environment

73
Q

what happens if an animal cell is placed in pure water or a dilute solution

A

water will enter the cell through its partially permeable membrane by osmosis as the pure water has a higher water potential. The cell will continue to gain water by osmosis until the cell membrane is stretched too far and the cell burst as it has no cell wall the withstand the pressure- cytolysis. This occurs in a hypotonic environment.

74
Q

what is active transport

A

movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

75
Q

why is ATP needed in active transport

A

ATP is needed to make the carrier proteins change shape to allow the transfer of molecules or ions

76
Q

when is active transport crucial

A

reabsorption of molecules into the blood after filtration in the kidneys

absorption of some products of digestion

loading inorganic ions from the soil into root hair cells

77
Q

what is co transport

A

the coupled movement of substances across a cell membrane via a carrier protein involving a combination of facilitated diffusion and active transport

78
Q

how does co transport happen in the epithelial cells lining the ileum

A
  1. the active transport of sodium ions from the epithelial cells into the blood lowers the concentration of sodium ion in the cell of the epithelial cells and generates a concentration gradient of sodium ions
  2. sodium ions then diffuse into the cells from the ileum by facilitated diffusion through a co transporter protein while carrying a glucose molecule along with them
  3. then the glucose can diffuse into the blood via facilitated diffusion
79
Q

what factors effect simple diffusion

A

surface area

diffusion pathway

concentration gradient

temperature`

80
Q

what factors effect the rate of facilitated diffusion

A

concentration gradient

number of channel or carrier proteins

81
Q

how are root hair cells adapted for diffusion

A

they have thin walls for a short pathway

a permanent vacuole to maintains high water potential

a specialised shape to increase SA

82
Q

how are epithelial cells of the small intestine adapted for diffusion

A

have microvilli to increase Sa

villi have constant blood supply to maintain high concentration gradient

83
Q

how are kidney cells adapted for faciliated diffusion

A

have high amount of channel proteins in the cell membrane

84
Q

how are neurones and muscle cells adapted for facilitated diffusion

A

have cell membranes containing lots of channel proteins

85
Q

name the 4 antigen presenting cells

A

pathogens
abnormal body cellls
cells from other individuals of the same species
cells that have been invaded by a virus

86
Q

what is an antigen

A

molecule that can stimulate an immune response by the body

87
Q

what are the two types of antigens and explain the difference

A

self-antigens are produced by the organisms body and dont stimulate an immune response

non self antigens are not produced by the organisms own body cells and stimulate an immune response

88
Q

what is antigen variability

A

antigens present on the surface change due to genetic mutations

89
Q

why is antigen variability a problem

A

poses a problem for the immune system as lymphocytes and memery cells that are specific to the shape of an anitgen will no longer be able to bind to them and therefore host gets infected again with the same disease

90
Q

what happens in phagocytosis

A

phagocyte recognises the foreign antigens on a pathogen

cytoplasm of the phagocyte moves arounf the pathogen engulfing it

pathogen is now contained in a phagocytotic vacuole

lysosomes fuse with the phagocytotic vacuole and the lysozymes hydrolyse and digest the pathogen

the phagocyte then presents the pathogens anitgens on its cell surface to activate other immune system cells and acts as an anitgen presenting cell

91
Q

where are t cells produced and mature

A

in the bone marrow before birth and mature in the thalamus

92
Q

what happens when a t cell is activated

A

t-lymphocytes are activated when they encounter their specific antigen that is being presented by one of the hosts cells

These activated lymphocytes divide by mitosis to increase in number and differentiate into two types of T cell:

1.Helper Tcells

2.Cytotoxic Tcells

93
Q

what is the role of a anitgen presenting cell

A

help recruit other immune cells to produce a specific response

94
Q

what do helper t cells do

A

assist other WBC in the immune system

release cytokines which stimulate:
1. the production of b memroy cells
2. activation of cytotoxic t cells

95
Q

what do cytotoxic t cells do

A

attatch to the foreign antigens and secrete perforins and granzymes to kill the cell

96
Q

where are b cells stored/made

A

in bone marrow and then spread out to spleen and lymph nodes

97
Q

what do b cells differenciate into

A

memory b cells- remain circulating in the blood for a long time and help spped up the secondary immune response

plasma cells- secrete lots of anitbodies into the blood but are short lived themselves

98
Q

what is the structure of an antibody

A

globular protein that have a quaternary structure with 2 light and 2 heavy polypeptide chains

99
Q

what is aggulintation

A

an antibody has two binding sites so it can bind to two pathogens at one time which means pathogens can be clumped together

100
Q

what does the binding of antibodies to antigens do

A

either neurtralises the pathogen or acts like a marker for phagocytes

101
Q

what is the celluar response

A

T cells and other immune cells they react with like phagocytes

101
Q

what is the humoral response

A

b-cells, clonal selection and the production of monoclonal antibodies

102
Q

what is involved in the primary immune response

A

when an antigen enters the body for the first time it causes an immune response which is slow as there arent any b-cells with the complementary antibodies for the pathogens antigen

eventually the body mounts a response big enough to kill the disease while the pateint is showing symptoms

the the t cells and b cells produce memory cells whcih remain in the body and will recognise the anitgen if infected with it again

103
Q

what is involved in the secondary response

A

the pathogen enters the body for a second time and the immune response starts again but is much quicker and stronger due to the memory cells circulting the blood and there should be no symptoms

b-cells circulating the blood
produce plasma cells very quickly so the needed antibodies are made quicker

memory t cells divide into the right type of t cell and to kill the pathogen

104
Q

what is a vaccine

A

a suspension of antigens put into the body artificially to produce an imune response

105
Q

what are the advantages and disadvanted to vaccines

A

advantages:
1. lifetime of protection
2. generally harmless and dont cause disease
3. help herd immunity and protect the vunerable

disadvantages:
1. people can have poor responses to them
2. they are often tested on animals
3. antigenetic variation can make them ineffective

106
Q

describe a live vaccine

A

containes a weakened athogen that multiplies slowly allowing the body to recognise it and prpoduce an immune response

107
Q

evaluate a live vaccine

A

+ tend to produce stronger and longer lasting responses

-They can be very unsuitable for people with weakened immune systems

108
Q

describe a inactivated vaccine

A

Contains whole pathogens that have been killed and they cannot cause disease

109
Q

evaluate inactivated vaccines

A

+ safer for people with weakened immune systems

  • dont trigger a long lasting immune repsonse and therefore boosters are often required
110
Q

what is herd immunity and why is it important

A

When a sufficiently large proportion of the population has been vaccinated which makes it difficult for a pathogen to spread within that population

+ Those who aren’t immunised are protected and unlikely to contract the disease as the levels are so low which allows individuals who cant get vaccines be protected

111
Q

what is active immunity

A

Acquired when an antigen enters through the body triggering a specific immune response

Naturally acquired through exposure to microbes or artificially acquired through vaccinations

The body produces memory cells alone with plasma cells giving the person long term immunity

The secondary response has a very high antibody concentration and takes a much shorter period

112
Q

what is passive immunity

A

Acquired without an immune response and are not produced by the infected person

As the persons immune system has not been activated then there are no memory cells that can produce antibodies in a secondary response

Artificial passive immunity occurs when a person us given an injection or transfusion of antibodies

Natural passive immunity occurs when a foetus receives antibodies across the placenta or when a baby receives the first breast milk with antibodies

113
Q

how is HIV spread

A

though bodily fluids

e.g sex, needles and a mother to her foetus through milk or the umbilical chord

114
Q

what is HIV made up of

A

two RNA strand, proteins, a viral envelope and attachtment proteins

115
Q

what are the steps to HIV replication

A
  1. viral RNA is injected into the cell when HIV attacthment proteins binds to human cell receptor site
  2. viral reverse trancriptase ezymes produce a DNA copy of the RNA
  3. the DNA copy is inserted into the chromomosomes of the cell
  4. cell divides and copies viral DNA
116
Q

what happens when the viral DNA in host cells becomes active in HIV

A

it takes control of the helper t cells and more HIV particles are produces which causes helper t cells to die and as b cells are no longer activated no antibodies are produces and this eventually leads to AIDS

117
Q

describe the stages of infection with AIDS symtom wise

A

inital infection is cold/flu like symptoms

dormancy- virus recplicating no symptoms but more sucepitable to infections

immunocomprimised- suffer from minor diseases

118
Q

how do antibiotics work

A

antibiotics interfere with the metabolism of bacterial cells while others prevent proteins synthesis

119
Q

what are monoclonal antibodies

A

Monoclonal antibodies are antibodies produced from a single group of genetically identical B-cells

120
Q

how can we use monoclonal antibodies to detect tumours

A
  1. Inject mice with human tumour cells
  2. Activates plasma cells to produce antibodies against human tumour cells
  3. Collected from the mouse spleen
  4. Plasma cells are fused with tumour cells to form a hybridoma
  5. Radioactive chemical is attached to antibody making them radioactively labelled
  6. A gamma ray camera is used to detect where the radioactively labelled antibodies have attached to a protein in human indicating where blood clots or tumours are.

You can also use this to treat them ny adding a drug to the antibodies and they will accumulate on the tumour markers

121
Q

how are monoclonal antibodies used in pregnancy tests

A
  1. Application area contains antibodies that are complimentary to the hCG protein bound to a blue coloured beam
  2. when urine is applied any hCG will bind to the antibody on the beads forming an antigen-antibody complex
  3. The urine moves up the stick to the test strip carrying any beads with it
  4. The test strip contains antibodies to hCG stuck in place (immobilised)
  5. If there is hCG preset the test strip turns blue because the immobilised antibodies bind to the hCG
122
Q

what are the ethical issues of vaccines

A

All vaccines are tested on animals before they can move onto human trials

Animal based substances are sometimes used in the production of vaccines, but some people disagree with this

Even at the human trial stage there is a risk the person gets disease or unpredicted side effects

When new epidemics happen, we struggle to decide who should be vaccinated first

123
Q

what are the ethical issues with monoclonal antibodies

A

Often tested on animals

Use animals to produce the cells for monoclonal antibodies

124
Q

describe the direct elisa tests

A

1.Antigens from patients’ blood are bound to the inside of a well

  1. A detection antibody with an enzyme attached that is complimentary to the antigen of interest is added
  2. Well is then washed out to remove any unbound antibodies
  3. Substrate solution is added, and a colour change will happen
125
Q

explain the indirect ELISA test to test for antibodies

A
  1. HIV antigens are bound to the bottom of the reaction vessel
  2. A blood plasms sample is taken from the patients and added to the reaction vessel
  3. Any HIV specific antibodies that are present in the blood will bind to the HIV antigens. These antibodies are known as the primary antibodies
  4. Any other antibody is unbound and washed out
  5. A second antibody with an enzyme attached is added to the reaction vessel and these are known as secondary antibodies and these bind to the primary antibody
  6. The reaction vessel is washed out again to remove any unbound secondary antibodies
  7. Add solution of substrate that reacts with enzyme to from a coloured product indicating hte patient has HIV as they have the antibodies in their blood for it.
126
Q

describe the indirect ELISA test for testing for antigens

A
  1. Antibodies are bound to the bottom of the reaction vessel
  2. Blood plasma sample is added
  3. Secondary antibody added
  4. Substrate added forming a coloured product

a level biology (6 decks)

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