All of studying cells Flashcards

Question

Role of cholesterol

Answer 1

Decreases permeability and increases stability of membrane more cholesterol= less fluidity of membrane

Answer 2

pores within the membrane that allow only specific molecules to move across by FD. Intrinsic Proteins have specific tertiary structure so are specific and can only transport molecules that are complementary to shape of channel proteins

Answer 3

aid transport of polar ions by FD and AT. Allow diffusion of larger molecules- attaches to binding site and changes shape, releasing the molecule through to the other side of the membrane

Answer 4

Composed of carbohydrates and proteins, important in cell recognition as act as antigens. Immune cells detect the specific shapes of glycoproteins to help identify self and non self cells

Answer 5

Passive process- does not require ATP, will stop when there are equal numbers of that specific molecule on each side- when they have reached equilibrium. Involves small non-polar lipid soluble molecules Definition: Net movement of molecules from an area of higher concentration to a lower concentration across a partially permeable membrane

Answer 6

temperature- increase in kinetic energy- faster rate of diffusion Surface area- the larger the surface area the more space for molecules to pass through Concentration gradient- as concentration difference increases, rate of diffusion increases diffusion distance- the shorter the diffusion distance, the faster molecules will travel from one area to the next. Phospholipid bilayer are all the same thickness

Answer 7

specific proteins help specific molecules to pass through the phospholipid bilayer. All have binding sites not active sites FD levels off when all the carrier proteins are saturated- number of carrier proteins will become a limiting factor

Answer 8

The net movement of water from higher water potential to lower water potential through a partially permeable membrane down a water potential gradient WP- water molecules and their ability to collide with a membrane

Answer 9

high- causes swelling and cell lysis- causes increase in mass low- results in shriveling of the cell- plant cell membrane pulls away from the cell wall isotonic-no net movement of water into and out of the cells

Answer 10

Movement of substances from low to high concentration moving against their concentration gradient. Requires carrier proteins. requires ATP- the hydrolysis of ATP allows protein to change shape and transport the molecule across the membrane

Answer 11

Bulk transport by exocytosis- uses golgi body to move large quantities of molecules

Answer 12

1. Na+ (sodium ions) are actively transported out of epithelial cell into the blood (by sodium potassium pump) 2. This creates a concentration gradient of Na+ (between lumen of the ilium and the epithelial cell) (Cotransporter proteins have 2 binding sites complementary to Na+ and glucose. Only when both molecules bind will the molecules be moved across the membrane) 3. Na+ and glucose enter by facilitated diffusion using (complementary) cotransporter proteins. 4. Na+ diffuse into the cell down its concentration gradient 5. Glucose moves into the cell against its concentration gradient / down an electrochemical gradient 6. Glucose moves into the blood by facilitated diffusion

Answer 13

Release toxins which can directly damage tissue Burst cells, replicating inside and take over by destroying host cells

Answer 14

A molecule, a protein, that stimulates an immune response that results in the production of a specific antibody If antigen not recognized the body will treat it as non-self and initiate an immune response leading to the destruction of the cell

Answer 15

Pathogen is engulfed by the phagocyte engulfed pathogen enters the cytoplasm of the phagocyte in a vesicle and forms a phagosome Lysosome fuses with phagosome releasing hydrolytic digestive enzymes lysosome enzymes hydrolyze the pathogen waste materials are released from the cell by exocytosis and antigens presented on the cell surface membrane and the phagocyte become an antigen presenting cell process is non-specific

Answer 16

a specific response to a specific antigen on the surface of a cell or pathogen that has been identified as non-self

Answer 17

what are they: These cells respond directly to a specific pathogen or its antigens or they respond to antigen presenting cells that present specifically complementary antigen to their receptors How they respond: Phagocyte engulfed and hydrolyses the pathogen and presents the antigen on the cell surface membrane TH cell with specific receptor molecule binds to presented antigen Once TH cell binds to the presented antigen it is activated, it then rapidly clones by mitosis .

Answer 18

a specific TH cell binds to presented antigen via its complementary receptor the cell is activated and clones to produce many TH cells with complementary receptors to its antigen

Answer 19

Specific Th cell binds to the antigen presenting cell release cytokines that attract phagocytes to the area of infection release cytokines that activate cytotoxic killer T cells activates a specifically complementary B cell form memory Th cells

Answer 20

locates and destroys infected body cells that present the correct antigen binds to antigen presenting cells releases perforin which creates holes in the cell membrane which destroys the antigen presenting cell

Answer 21

Involves the activation of B cells to produce antibodies 1. specific Th cell with the correct receptor binds to presented antigen and then locates and activates specifically complementary B cells The Th releases cytokines that signal the B cell to clone by mitosis the B cell then differentiates into plasma cells, producing and secreting a vast quantity of antibodies and memory cells, remain in the body to release antibodies when secondary infection approaches

Answer 22

protein made in response to a foreign antigen- has binding sites which bind specifically to an antigen. a specific antibody is produced by a specific plasma cell

Answer 23

quaternary- has a constant region and variable regions so different tertiary structure as have different primary structure. The variable region and therefore the binding site is specific for each antibody Binds to form antigen antibody complex

Answer 24

Agglutination- specific antibodies bind to antigens on pathogen and clump them together Opsonisation- marking of pathogens so phagocytes recognize and destroy the pathogen more efficiently

Answer 25

The activation of memory cells to produce antibodies- rapid and extensive production of antibodies Effective as most pathogens have the same antigens on their surface and so are recognized by memory cells when re-infection occurs

Answer 26

Antigenic variability- gene mutations change tertiary structure of antigens specific to B cells- no longer complementary to produce antibodies.

Answer 27

P V A No exposure to antigen: Exposure to antigen Antibodies are given: Antibodies are produced No memory cells are provided: Memory cells are produced Short term: Long term Fast acting: Takes time to develop

Answer 28

Contain antigens from dead, weakened or attenuated pathogens pathogen is engulfed by phagocyte and displayed on an antigen presenting cell a specific t helper cell binds to antigen and stimulated B cells through the release of cytokines. B cells divide by mitosis to produce plasma cells and memory cells plasma cells produce and release antibodies memory cells recognize antigen on second infection

Answer 29

If enough individuals in the population are vaccinated (85%) then there is little chance of the disease spreading, therefore even non-vaccinated individuals will be protected

Answer 30

Development using the testing on animals Human testing available to everyone or only those who can afford balancing risk of side effects with benefits vaccination programmes compulsory? Loss of genetic variability through eliminating and organism

Answer 31

Antibodies that all have the same tertiary structure Use: research, immuno assays, diagnosis, targeting drugs, killing specific cells, isolating specific chemicals

Answer 32

Antigen-coated well, specific antibody binds to antigen, enzyme-linked antibody binds to specific antibody, substrate is added and converted by enzymes into coloured product- rate of colour formation is equal to the amount of specific antibody wash in-between to remove excess antibody

Answer 33

Antibody-coated well, add antigen to be measured, add enzyme conjugated secondary antibody, add substrate and measure colour

Answer 34

Structure: Attachment proteins, lipid envelope, reverse transcriptase, HIV RNA, capsid Replication: Attachment proteins on HIV binds with a protein receptor found on Th cells Capsid fuses with cell-surface membrane and releases viral RNA and enzymes into the helper T cell The HIV's reverse transcriptase converts Viral RNA into cDNA using host nucleotides and cDNA converted to dsDNA by DNA polymerase Viral cDNA moves into nucleus of T cell and is inserted into host cell genome. the person is now infected Transcription of viral DNA into mRNA which is translated to produce HIV proteins. The infected t helper cell starts to manufacture HIV proteins Particles break away with a section of the host cell membrane which forms the lipid envelope Reduces the number of Th cells

Answer 35

Not a pathogen- can be detected by screening for number of TH cells Cell mediated immunity of an individual is compromised More HIV, destruction of more TH cells, less activation of B cells, less able to destroy pathogen

Answer 36

G1 phase Cell increases in size and new biomass is made (proteins) S phase DNA replicates by semi-conservative DNA replication G2 phase Cell prepares for division, synthesis & stores of ATP and new organelles synthesised.

Answer 37

A gene is a section of DNA that codes for one specific polypeptide (protein). The base sequence of DNA on the DNA codes for the sequence of amino acids in a protein.

Answer 38

A chromosome is an independent DNA molecule which has been supercoiled into a condensed form

Answer 39

Homologus chromosomes –have the same genes in the same gene loci (positions) but may have different alleles (versions) of the genes. (one chromosome is Maternal and the other is Paternal)

Answer 40

Increasing cell numbers and growth of an organism · Repair of damaged tissues (not cells) · Replacement of worn out/ dead cells It is also used by some organisms for asexual reproduction. All the offspring will be identical. This tends to occur in favourable, stable environments (where there is no environmental change).

Answer 41

1) The nuclear membrane starts to break down. 2) The centrioles start to move to the poles of the cell and make spindle fibres 3) The chromosomes supercoil and condense / shorten / thicken and become visible. 4) Each chromosome appear as 2 identical sister chromatids joined at the centromere

Answer 42

The centrioles complete the production of spindle fibres (contractile protein fibres) 2)The chromosomes are attached to the spindle fibres by their centromere 3) the chromosomes align down the equator of the cell.

Answer 43

The spindle fibres contract/shorten. 2)The centromere splits 3)The identical sister chromatids are pulled to opposite poles 4) making a “V” shape

Answer 44

A nuclear membrane starts to reform around each set of chromosomes 2)The chromatids / chromosomes unwind / uncoil / become longer / thinner and become invisible

Answer 45

the cell surface membrane pinches together, the cytoplasm divides forming two daughter cells.

Answer 46

During prophase, chromosomes supercoil and condense to become visible; 2. Chromosomes appear as 2 identical sister chromatids joined by a centromere; 3. During metaphase chromosomes line up on the equator of the cell; 4. Chromosomes attach to the spindle fibres; 5. By their centromeres; 6. During anaphase, the centromere splits; 7. Sister chromatids are pulled to opposite poles of the cell making a V shape; 8. During telophase, chromatids uncoil and become thinner;

Answer 47

Tumour suppressor genes code for proteins that slow down the cell cycle. · Proto-onco genes code for proteins that speed up the cell cycle.

Answer 48

cells that undergo uncontrolled mitosis

Answer 49

DNA replication, spindle formation, Cytokinesis or other processes linked to mitosis.

Answer 50

* replication of the circular DNA (not associated with histones) and of plasmids * division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.

Answer 51

Mitotic index = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐𝑒𝑙𝑙𝑠 𝑖𝑛 𝑃𝑀𝐴𝑇/𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑣𝑖𝑠𝑖𝑏𝑙𝑒 𝑐𝑒𝑙𝑙𝑠

Answer 52

M1 X V1 = M2 X V2 M1 = Desired diluted concentration (mol dm-3) V1 = Desired Volume (cm3) M2 = Original concentration (mol dm-3) V2 = Unknown Volume of stock solution (cm3)

Answer 53

In a meiotic division, the DNA is replicated in S phase (interphase) of the cell cycle. The chromosomes then go through two nuclear divisions. Each division has a prophase, metaphase, anaphase and telophase. In the first meiotic division, the homologous chromosomes pair up and are separated (INDEPENDENT SEGREGATION 2n to n). In the second division, the chromatids are separated.

Answer 54

Random fertilizations of haploid gametes produced by meiosis crossing over independent segregation

Answer 55

1. The homologous chromosomes associate (Bivalent is formed). 2. Chiasmata form (Chromosomes entangle / twist). 3. Equal lengths of (non-sister) chromatids / alleles are exchanged. 4. Producing new combinations of alleles.

Answer 56

Homologous chromosomes pair up/ bivalents form; 2. Independent segregation occurs; 3. Maternal and paternal chromosomes are reshuffled in any combination; 4. Crossing over leads to exchange of parts of (non-sister) chromatids/alleles between homologous chromosomes; 5. (both) create new combinations of alleles.