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topic 2 (cells) Flashcards

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1
Q

what is the formula for magnification?

A

magnification= image size/object size

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2
Q

what is the definition of resolution and what how does a high resolution effect the image?

A

the minimum difference between two objects for them to be seen as separate objects. A high resolution means greater clarity

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3
Q

what is the first step of cell fractionation and what occurs?

A

homogenation-the cells are broken down via a blender (homogeniser). this releases the organelles from the cell. This solution (homogenate)is then filtered to remove whole cells and debris

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4
Q

what is the 2nd step of cell fractionation and what occurs?

A

in Ultracentrifugation the homogenate is spun in a centrifuge at a low speed where the heaviest organelle forms a pellet at the bottom. the rest (supernatant) is then removed and the process is repeated.

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5
Q

How are cells stored in cell fractionation?

A

Cold temperatures to reduce enzyme activity
Buffered solution keeps pH constant and avoids damaging protein/cell structure
solution of same water potential to prevent bursting shrinking of organelles

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6
Q

What are the advantages of electron microscope over light microscope?

A

the electron beam has a short wavelength and therefore electron microscope has better resolution.
the beam can be focused using electromagnets.

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7
Q

what are the limitations of transmission electron magnification?

A

living specimens cannot be observed
the specimens has to be stained
the specimen must be extremely thin

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8
Q

what are the structures and functions of the nucleus?

A

the nuclear envelopes is a double phospholipid membrane that controls what goes in and out of the nucleus.
nuclear pores allow bigger molecules to pass though
nucleolus small sphere that makes rRNA and assembles the ribosomoses.
Nucleoplasm (jelly) makes up the rest

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9
Q

what are the structures and functions of the mitochondria?

A

Has a double phosopholipid bilayer.
the inner layer of the membrane has folds called cristae. these provide a large surface area for the attachment of enzymes
Matrix makes up the rest . It contains ribosomes and DNA and it produces its own proteins

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10
Q

what are the structures and functions of the golgi appartus?

A

contains flattened membranous sacs.
transport vesicles carry proteins and lipids from the s&r endoplasmic reticulum to the golgi lumen. The golgi sorts and modifies the proteins and lipids.
the golgi vesicles transports the final products to its target

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11
Q

what are the structures and functions of the lysosomes?

A

vesicle with a single membrane .
contains lysozymes(enzyme)
function is to hyrdrolyse material injected by phagocytic cells

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12
Q

what are the structures and functions of the ribosomes?

A

can be found in cytoplasm or associated with Rough endplasmic reticiulum.
80s is found in eukaryotic cells
70s is found in prokaryotic cells

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13
Q

what are the structures and functions of the smooth endoplasmic reticulum

A

contains a series of flattened sacs (cisternae)
synthesis, store and transport lipids and carbohydrates

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14
Q

what are the structures and functions of the rough endplasmic reticulum

A

contains a series of flatenned sacs
Has ribosomes on its membrane
provide a large surface area for the synthesis of proteins and gylcoproteins
provide a pathway for the transport of proteins theough the cell

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15
Q

what are the structures and functions of the chloroplasts?

A

chloroplast envelope is a double plasma membrane that surrounds the cell.
stacks of thylakoid (discs) that makes up the gramnum
thylakoid contains chloroplasts
the stroma fluid filled matrix
function is to absorb light for photosynthesis and produce sugars

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16
Q

what are the structures and functions of the cell wall

A

made up of cellulose (glucose B)
provides structural support

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17
Q

what are the structures and functions of the vacuole

A

surrounded by membrane called tonoplast
contains solution of salts and sugars( cell sap)
allows cell to remain rigid

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18
Q

what are the structures and functions of the capsule in a prokaryotic cell?

A

protective slimy layer that helps the cell to retain moisture and adhere to surfaces

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19
Q

what are the structures and functions of the flagellum

A

tail like structure which rotates to move the cell

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20
Q

what is a virus?

A

Made up of nucleic acid.Surround by a capsid. Not considered living because they cannot reproduce independently and require host cell.

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21
Q

what does mitosis produce?

A

2 daughter cells that have the same amount of chromosomes as the parent cell

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22
Q

what are the stages of the cell cycle?

A

interphase G1 cell grows
S Dna synthesis
G2 Chromosomes replicated
mitosis prophase
metaphase
Anaphase
Telophase
Cytokenisis

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23
Q

What happens in the prophase?

A

nuclear envelope breaks down
nucleolus dissapears
chromosomes become shorter and fatter
spindle fibres appear

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24
Q

what happens in the metaphase?

A

chromosomes line along middle
chromosomes condense to their maximum
Attachrched to spindlefibre by centromere

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25
what happens in the anaphase?
chromatids line up at polar ends of spindle fibre V-shaped chromatids that have been pulled part at the centromere
26
what happens in the telophase?
nuclear envelope reappears nucleolus reappears spindle fibres disintergrate
27
what happens in cytokinesis?
cytoplasms divide into 2 2 daughter cells are produced
28
how does binary fission occur?
circular DNA and plasmids are replicated the cell membrane begins to grow between 2 dna molecule. it begins to pinch inwards dividing the cytoplasm into 2 A new cell wall forms between the dna molecules leaving two identical daughter cells
29
how do drugs affect the cell cycle and how can this be used to treat cancer?
preventing dna from replicating(G1) inhibitng the metaphase stage of mitosis by intefering with spindle formation
30
what do phospholipids do in a phospholipid bilayer
hydrophillic heads on the outside,hydrophobic heads on the outside. allow lipid solouble substances in & out prevent water solouble water molecules fromgoing in and out
31
what do proteins do in a phospholipid bilayer?
Form protein channels which allow water solouble ions to pass through carrier proteins (active transport)that bind to ions or molecules and change shape to move across the membrane structural support cell surface receptors for identifying cells
32
what do cholesterol do in a phospholipid bilayer?
add strength to the membrane very hydrophobic so reduce water loss and ion loss
33
what do glycolipid do in a phospholipid bilayer?
maintain stability of the membrane act as recognition sites
34
what do glycoprotein do in a phospholipid bilayer?
allows cells to recognise each other helps cell to attach to each other and form
35
definition of diffusion
the net movement of molecules from an area of high concentration to an area of low concentration until evenly distributed
36
factors of diffusion
concentration gradient temperature surface area of the cell membrane(pathway)
37
definition of osmosis
the movement of water from an area where it has high water potential to an area where it has low water potential through a semi permeable membrane
38
what is the highest water potential?
the highest water potential is 0 the lower the water potential the more negative its value is.
39
definition of active transport
the movement of molecules from an area of low concentration to high concentration (against concentration gradient). using ATP and carrier proteins.
40
how do carrier proteins assist in active transport?
the molecule binds with the receptor site on the carrier protein. on the other side an ATP molecule becomes attatched.The ATP molecule converts to ADP and Pi. this changes the shape of the protein and opens to the opposite side of the membrane. the molecule is released on the other side. the phosphate ion is released reverting the shape of the protein
41
what increases the rate of facillitated diffusion,diffusion and active transport at the illeum?
epithilial cells line the membrane. these have microvilli which can increase the surface area for more carrier proteins
42
how is glucose concentration maintained ?
the illeum is has a concentration than the blood. also the fact that the blood is being constantly pumped around the body means that it is maintain ed
43
what is the na/k pump?
when sodium is being actively transported out the cell while potassium is being actively transport into the cell
44
why is glucose co transported into the epithelial cell and what conditions make it effective?
all the glucose cannot be absorbed by the body by normal facillitated diffusion co transport is used when their is concentration gradient when it cannot diffuse into the lumen anymore. the epithilial cell is line with microvilli and mitochondria to help
45
What is co transport at the illeum and how does this help absorb glucose
Sodium is actively transported out of the epithilial cell in the illeum using a carrier protein and ATP. However because it is at a low conc in the illeum and high at the lumen. It is then facillitated diffusion back in carrying glucose/amino acids via another carrier protein. the glucose/amino acid is then faciliitated diffusion out as it is at high concentration in the eptithilal cell in the illeum and low conc in the blood capillary. the sodium is actively transported out and the cycle continues.
46
what are the 2 defence mechanisms and how are they different?
specific is specific to the pathogen and takes longer.(T lymphocytes and B lymphoctyes) non specific is a general response and is immediate (phagocytosis)
47
how do lymphocytes develop to recognise cells from its own body from birth?
Infection is rare as the fetus its protected from the rest of the world. this means the lymphoctyes are mainly colliding with its own body cell. Some of these lymphocytes will have the receptors that fits its own body cells.These are suppressed or killed.Leaving none that fits its own body cells. For adults lymphocytes are produced in the bone marrow .any that show signs of immune response undergo cell death(apoptosis). Preventing them from maturing
48
how does phagocytosis occur?
phagocyte is attracted to the chemical products of the pathogen. the receptors on the surface attach to the pathogen . the pathogen is engulfed making a phagosome. the lysosymes in the phagocyte release lysozymes which hydrolyse the cell wall and the rest of the content is absorbed by the phagocyte
49
what are antigens ?
complex molecules on the cell surface membane used to differentiate between self and foreign cells.
50
what are the two lymphocytes and what are the differences?
B lymphocytes associated with humoral immunity and the production of antibodies. matured in bone marrow T lymphocyte associated with cell imediated matured in thymus gland
51
how does cell mediated immunity happen?
phagoctyes have its pathogens antigens on its own cell membrane . T helper cells receptors fit exactly onto these antigens. this activate T cells to divide by mitosis and form a clone of T cells.From here T cells can activate B cells to release antibodies,release cytoxic T cells, stimulate phagocytosis,develop memory cells to for a rapid response for the same pathogen
52
what do cytotoxic T cells do?
kill abnormal cells or body cells that are infected by pathogens by the protein perforin that makes holes in the cell membrane that makes it freely permeable hence killing it by water overflow
53
what do plasma cells do?
produce and secrete specific antibodies
54
what do memory cells do?
they are a secondary immune response .move around the blood. If they come across the specific antigen they divide into plasma cells and more memory cells. these plasma cells can secrete the specific antbody.memory cells allow for long term inmmunity by reducing time needed to make the specific antibody.
55
how does humoral immunity work?
the specific antigens of a pathogen meet the specific B cell. the B cell engulfs it and shows the pathogens on its own membrane. this attracts the T helper cells which attach to the antigens. Activating the B cell to divide by mitosis to give a clone of plasma cell. these can produce and secrete the antibodies. The antibodies attach to the antigens on the pathogen destroying them. Memory cells are also be produced
56
Describe all the parts of an antibody?
They are made of 4 polypeptide chains. 2 light and short chains and 2 long and heavy chains. it has a specific binding site that binds with the antigen the binding site varies and therefore is called the variable region the rest of the antibody is called the constant region and this binds to the b cell
57
what is a monoclonal antiboidy?
An antibody that is not produced inside the body and can be cloned and isolated
58
how do antibodies destroy specificpathogens
they cause agglutination which clumps up bacterial cells together allowing phagocytes to locate them easier. they can also act as markers allowing phagocytes to engulf the bacteria
59
how can monoclonal antibodies be used to treat cancer?
antibodies can be created that are specific to the antigen of the cancer. These can be given to the patient and attach themselves to the cancer cells .this can stop their rapid growth. e.g men with prostate cancer produce a high level of a protein called PSA.a monoclonal antibody can be used to measure and lead to a diagnose
60
Ethical issues of monoclonal antibodies
using mice to make them (injecting them with cancer) Has caused many deaths Testing for them is extremely dangerous
61
what is passive immunity?
when the antibodies are aqquired without having to generate themselves yourself. no contact with the pathogen/antigen is required. However their is no long lasting immunity as their are no memory cells made. e.g anti-venom from a snake bite
62
what is active immunity and what are the 2 types?
Natural active immunity is when the antibodies are produced after contact with the pathogen under normal circumstances Artificial active immunity is when the pathogen is introduced unnaturally (immunisation) and triggers the body to produce its own antibodies,
63
what is herd immunity?
when a sufficient amount of the population is vaccintaed making it hard for the pathogen to spread. this is important as not everyone can be vaccinated (babies ,ppl with weak immune systems) the percentage of people required to be vaccinated for each disease to achieve herd immunity is different.
64
why might a vaccine not be effective?
the pathogen is constantly mutating making it hard to match the anibody A person may have a immune system the pathogen can hide from the vaccine their may be too many varieties of the same pathogen
65
What are the ethical issues surrounding vaccines?
use of animals when making them the clinical trials /testing of them should they be compulsary long term side effects
66
successful vaccination program involves?
Very few side effects herd immunity can be obtained ecnomocially available in sufficient quantities to immunise the vulnerable population
67
what is the structure of HIV?
circular lipid envelop with attachment proteins around it on the inside is a protein layer(caspid) which has 2 RNA inside it and an enzyme reverse transcriptase which catalyses RNA to DNA.
68
how does HIV cause AIDS?
HIV targets the helper t cells causing them drop in numbers. without the helper t cells .B cells and Cytotoxin t cells cannot be activated. this means the body is open to attack and less harmful pathogens are considered extremely harmful.
69
Describe the ELISA test (it tests for a specific protein /antigen and how much their is)?
monoclonal antibodies bind to bottom of test plate antigen molecules bind to specific antibody.rinse excess mobile antibodies with enzyme attach to monoclonal antigens that are fixed on monoclonal antibodies.rinse excess add substrate for the enzyme the color change indicates antigen presence
70
why are antibiotics not useful against HIV/viruses?
Antibiotics produce peptide cross linkages which weaken the cell wall of bacteria. bacteria has murein its cell wall that stop water from coming in via osmosis.When weakened water fills the bacterial cell unti it bursts. HIV is in a host cell and cannot be targeted its cell wall is also made of a protein coat
71
How does HIV replicate?
HIV enters the blood stream HIV binds to protein (CD4) this is in t helper cells HIV the protein caspid fuses with cell surface membrane RNA and enzymes from HIV enter htc reverse transcriptase converts rna to dna the dna enters the htcs nucleus where it is inserted this hiv dna creates mrna which has instructions for creating viral proteins and the rna goes in2 new hiv the mrna leaves via nuclear pores and uses the cell proteins synthesis to make new hiv molecules
72
what are ribosomes made of ?
RNA and protein

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