Topic 2 - Cells

Question 1

Lysosomes

Answer 1

Membrane-bound organelle which releases hydrolytic enzymes (lysozymes)

Question 2

Viruses structure

Answer 2

They are non-living and acellular particles, they include:
.Genetic material
.Attachment proteins
.Capsid

Question 3

How do prokaryotes differ to Eukaryotes (4 differences)

Answer 3

.Cytoplasm lacks membrane bound organelles
.Smaller ribosomes (70s)
.No nucleus, instead a single circular DNA molecule free in the cytoplasm, not associated with histones
.Cell wall made from murein, a glycoprotein

Question 4

Mitosis

Answer 4

Part of the cell cycle where eukaryotes divide into 2 daughter cells, with identical copies of parent cell DNA

Question 5

Binary fission

Answer 5

Occurs in prokaryotes, and is where:
.Circular DNA and plasmids replicate
.Cytoplasm divides, producing 2 daughter cells with a single copy of circular DNA and variable copies of plasmids

Question 6

Role of cholesterol

Answer 6

Restricts movement of other molecules making up the membrane

Question 7

Différents ways of movement across membranes (5)

Answer 7

.Simple diffusion
.Facilitated diffusion (uses carrier and channel proteins)
.Osmosis
.Active transport (Involves carrier protein and hydrolysis of ATP)
.Co-transport (illustrated in cells lining ileum by absorption of sodium and glucose)

Question 8

Ways cells can be adapted for rapid transport (3)

Answer 8

.Increase surface area
.Increase number of protein channels/carrier proteins
.Large number of mitochondria to produce ATP for active transport

Question 9

Antigen

Answer 9

A protein on the cell surface membrane which triggers an immune response

Question 10

Antigen variability

Answer 10

A mutation occurs causing antigens to change shape, so antibodies will no longer be complementary in shape

Question 11

Cell mediated response

Answer 11

Response of T lymphocytes to a foreign antigen (T cells binding to APC then cloning itself, cloned helper T cells stimulate cytotoxic T cells, B cells and phagocytes to target virus infected body cells )

Question 12

Humoral response

Answer 12

The response of B cells to a foreign antigen, clinal selection and release of monoclonal antibodies

Question 13

How do antibodies destroy antigens

Answer 13

Agglutination occurs, forming Antigen-antibody complex leading to destruction of the antigen (easier for phagocytosis to occur)

Question 14

Active and Passive immunity

Answer 14

.Active immunity is when your immune system is exposed to the antigen, and produces its own antibodies. This is much slower but long term

.Passive immunity is when antibodies are injected into immune system. Is much faster but only short term

Question 15

Antibiotics

Answer 15

These target metabolic pathways and cell structures (such as cell wall)