Membranes, Cell Cycle (Lecture 7)

Question 1

What is Facilitated diffusion?

Answer 1

• passive (no energy required, driven by concentration gradients)
• solutes move through membrane proteins

Question 2

What are the 3 ways of facilitated diffusion?

Answer 2

1. Channel proteins
2. Gated channel proteins
3. Carrier proteins

Question 3

What is channel proteins (aquaporin)?

Answer 3

• form hydrophilic channels in the membrane through which water and ions can move
• an aquaporin is a water channel. Water molecules move through the channel by being handed off to a succession of hydrogen-bonding sites on the channel in this protein

Question 4

What is carrier proteins?

Answer 4

• (1) In conformation so that binding site is exposed toward region of higher concentration
• (2) solute molecule binds to carrier protein

Question 5

About primary (1) active transport?

Answer 5

• requires energy
• things move against their concentration gradient
• two types of active transport:
  ->primary - uses ATP
  ->secondary - uses electrochemical gradients

Question 6

1(primary) active transport example: sodium-potassium pump

Answer 6

• moves sodium ions (NA+) out of cell )—— Both ions are moved against their concentration gradients,
• moves potassium ions (K+) into cell ) —— So energy is needed
• the transporter uses ATP to do this

Question 7

About secondary (2) active transport?

Answer 7

• does not use ATP
• uses ion gradients (electrochemical) for energy
• energy released as an ion moves with its concentration gradient is used to drive movement of a solute against its concentration gradient

Question 8

Symport and antiport in secondary active transport?

Answer 8

Symport - the transported solute moves in the same direction as the gradient of the driving ion
Antiport - the transported solute moves in the direction opposite from the gradient of the driving ion

Question 9

About exo/endocytosis

Answer 9

1. Exocytosis
2. Endocytosis types:
   A) receptor-mediated (LDL cholesterol)
   B) bulk-phase (pinocytosis) (pino = drink)
   C) phagocytosis (phago = eat)

Question 10

What is signal transduction?

Answer 10

Signal —> transduction—-> response

1. Reception - binding of a signalling molecule with specific receptor of target cells
2. Transduction - signal is changed into a form for eliciting the cellular response. Typically involves a signalling cascade, a sequence of reactions that include several different molecules
3. Response - transduced signal causes a specific cellular response that depends on the signalling molecule and the receptors of the target cell

Question 11

What is a kinase?

Answer 11

An enzyme that phosphorylates other proteins things using ATP

Question 12

What are Homologous chromosomes?

Answer 12

Same order of genes, but may are different versions (alleles)

Question 13

Chromosomes and ploidy (humans)?

Answer 13

Humans are diploid creatures with 23 chromosomes

Question 14

What are sister chromatids?

Answer 14

A creature with one chromosome

Question 15

What is the cell cycle of a eukaryotic cell?

Answer 15

Mitosis and interphase

Question 16

What are the stages of mitosis?

Answer 16

Prophase
Metaphase
Anaphase
Telophase
- (late anaphase and all of telophase is when cytokinesis occurs)

Question 17

What are the stages of interphase?

Answer 17

Interphase begins in daughter cells
1. G1
2. S
3. G3

Question 18

What is the G1 phase?

Answer 18

G1 phase is a period of growth before DNA replicates. The cell makes various RNAs, proteins, and other types of cellular molecules but not DNA (the G in G1 stands for gap, referring to the absence of DNA synthesis)

Question 19

What is the S phase?

Answer 19

If the cell is going to divide, DNA replication begins. During S phase, the cell duplicates each chromosome, including both the DNA and the chromosomal proteins, and it also continues synthesis of other cellular molecules

Question 20

What is the G2 phase?

Answer 20

Refers to the second gap in which there is no DNA synthesis. During G2 the cell continues to synthesize RNAs and proteins, including those for mitosis, and it continues to grow. The end of G2 marks the end of interphase; mitosis then begins

Question 21

What are the three centromeres and what do they do?

Answer 21

1. Centromere - constricted region of chromosome linking sister chromatids
2. Kinetochore proteins assemble at the centromere
3. MTs - attach to kinetochores