3.2 Cells Flashcards

Question

Cell fractionation steps

Answer 1

1. Homogenisation - cells are broken open to release organelles using a blender 2. Filter to remove large cell debris 3. Placed in centrifuge and spun at low speed 4. Densest organelle forms pellet at bottom 5. Remove pellet and spin supernatant at a faster speed 5. Repeat

Answer 2

Cold - reduce enzyme activity which could damage organelles Isotonic - prevent osmosis which could cause organelles to shrink/burst Buffered - Prevent pH change which could damage organelles

Answer 3

G1 - Growth S - DNA synthesis G2 - Growth and preparation for mitosis M - Mitosis

Answer 4

1. Prophase. Chromosomes condense and become visible. Centrioles move to opposite poles of cell 2. Metaphase. Chromosomes line up along equator of cell. Spindle fibres attach to centromere 3. Anaphase, spindle fibres shorten, causing the centromere to divide in two, so individual chromatids are moved to opposite poles. Requires ATP 4. Telophase. Nuclear membrane reforms, cytoplasm splits in two to form two identical daughter cells

Answer 5

1. Replication of circular DNA and of plasmids 2. Division of cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of plasmids

Answer 6

Fluid - Components can move along/across phospholipid bilayer Mosaic - composed of many different molecules

Answer 7

Phospholipid bilayer Glycoproteins and glycoplipids (cell recognition) Cholesterol Channel and carrier proteins (integral proteins) Peripheral proteins (mechanical support)

Answer 8

Small lipid soluble molecules

Answer 9

Simple diffusion Osmosis Active transport Facilitated diffusion Cotransport

Answer 10

Net movement of molecules from an area of higher concentration to an area of lower concentration. Passive.

Answer 11

Net movement of molecules from an area of higher concentration to an area of lower concentration using channel/carrier proteins. Passive.

Answer 12

The net movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane.

Answer 13

Water potential of a solution if more positive than the cell. TURGID.

Answer 14

Water potential of a solution is more negative than the cell. FLACCID.

Answer 15

Movement of substances from an area of lower concentration to an area of higher concentration using ATP and a CARRIER protein.

Answer 16

1. Molecule binds to a complimentary receptor. 2. ATP binds to carrier protein from inside of cells and is hydrolysed to ADP and Pi 3. Causes the carrier protein to change shape, releasing the molecule to the other side 4. Phosphate ion is released, so carrier protein returns to original shape

Answer 17

1. Sodium ions actively transported out of epithelial cell into blood 2. reducing sodium concentration inside of cell 3. Sodium ions diffuse into the cell from the lumen and are co-transported with glucose/amino acid 4. Glucose then moves by facilitated diffusion into the blood.

Answer 18

- Increase in surface area - Increase in number of channel and carrier proteins in the membrane

Answer 19

Pathogens Foreign cells Tumour cells Toxins Allergens

Answer 20

Molecules (usually proteins) that trigger an immune response

Answer 21

A pathogens DNA can mutate frequently. If a mutation occurs in the gene which codes for a protein, then the shape of the antigen will change. This means any previous immunity to this antigen is no longer effective as memory cells will have memory of old antigen shape

Answer 22

Physical barriers - skin Chemical barriers - saliva, tears, stomach acid Phagocytes

Answer 23

1. Phagocyte receptors bind to antigens on pathogen 2. Phagocyte engulfs pathogen, forming a phagosome 3. Lysosomes fuse with phagosome and release hydrolytic enzymes, destroying the pathogen 4. Pathogen antigens are modified and displayed on phagocyte cell surface membrane

Answer 24

Bone marrow

Answer 25

1. Helper T cell binds to pathogen antigens on phagocyte 2. Stimulates T cell to divide by mitosis, forming many clones 3. Clone helper T cells differentiate into Helper T cells, memory cells or cytotoxic T cells

Answer 26

Release perforin which makes holes in cell surface membrane if pathogens. Cell may burst or shrink and die.

Answer 27

1.Helper T cells bind to complimentary B cell receptor 2. Stimulates B cell 3. B cell divides by mitosis into plasma cells which are clones 4. Plasma cells release antibodies complimentary to antigen 5. Some plasma cells remain as memory cells 6. Antibodies attach to pathogen and destroy them

Answer 28

Quaternary protein released by plasma cells in response to antigens. They can agglutinate pathogens.

Answer 29

Quaternary proteins - 4 polypeptide chain Variable region - antigen binding sites Constant region Heavy and light chains 2 variable regions so can bind to two antigens, clumping pathogens together - agglutination

Answer 30

Will divide by mitosis and make plasma cells rapidly if they collide with an antigen they have previously encountered

Answer 31

Primary response is much slower as it needs time to identify, select and clone the specific lymphocytes needed. Primary response is also less strong. Secondary response involves memory cells.

Answer 32

- Active involves formation of memory cells, passive doesn't - Active involves production of antibodies by plasma cells in response to antigen - Passive involves introduction of antibodies from outside the body - Active long term as antibodies produced in response to antigen - Passive short term as introduced antibodies are broken down - Active can take a while for effects, passive is rapid

Answer 33

Artificial - Vaccination Natural - Normal body response to antigen

Answer 34

Artificial - Antibodies from mother through placenta Natural - Antitoxin for snake bite

Answer 35

When small amounts of weakened or dead pathogen or antigens are introduced into the body

Answer 36

1. Antigen/pathogen introduced 2. Exposure to antigen activates B cells to go into clonal expansion and differentiation 3. B cells undergo mitosis and make clones of plasma cells, which release antibodies 4. Some plasma cells remain in the blood as memory cells 5. Next time antigens are present, memory b cells produced antibodies rapidly, so no/few symptoms

Answer 37

If enough of the population are vaccinated, the pathogen cannot spread easily amongst the population, providing protection for people who cannot take vaccines.

Answer 38

Genetic material Reverse transcriptase enzyme Capsid Envelope Attachment proteins (CD4)

Answer 39

1. HIV attachment proteins bind to CD4 receptors on helper T cell 2. HIV RNA injected into cell alongside enzymes 3. Reverse transcriptase converts viral RNA to DNA 4. Integrase inserts viral DNA into cellular DNA 5. Viral proteins produced 6. Viral particles assembled and released

Answer 40

Interferes with the normal functioning of the immune system. T helper cells are destroyed, leaving the person vulnerable to infections and cancer. It is this that leads to death rather than HIV directly.

Answer 41

A specific type of antibody produced by a single clone of B cells, that binds to only one specific antigen. They are proteins with binding sites with complimentary shapes to antigens.

Answer 42

Medical treatment Medical diagnosis Pregnancy tests

Answer 43

- Monoclonal antibodies are produced with a binding site complimentary to antigen of cancer cell - Antibodies given to patient and attach to cancer cells - Prevents chemicals binding to cancer cells that could cause uncontrolled cell division - So prevent cancers growing

Answer 44

- Monoclonal antibodies are produced with a binding site complimentary to antigen of cancer cell, but also have a drug/fluorescent dye attached - Cancer drugs are delivered directly to the cancer and kill them - Reducing side effects from conventional methods - or cancer is highlighted for surgery/after surgery

Answer 45

1. Fix antigen to bottom of beaker 2. Add complimentary antibody (WASH) 3. Add 2nd antibody which has an enzyme attached (WASH) 4. Add substrate complimentary to enzyme (WASH) 5. Depth of colour change indicates positive result

Answer 46

-ves Use of animals in production +ves Better treatment of cancers in humans Detection of disease

Answer 47

No cell surface membrane

Answer 48

Have no metabolic reactions

3.2 Cells Flashcards

(75 cards)