Cell Membrane

Question 1

What is Homeostasis?

Answer 1

a constat stae is maintained

Question 2

What are the other functions of the cell membrane (minus being semi-permeable)? (3)

Answer 2

• provides structual support
• recognized foregin materials
• communicate with the cells

Question 3

What is the lipid bi-layer

Answer 3

the phospholipid’s orgainized ontotowo layers with the hydrophobic tias int eh center and the hydrophilic head facing into and out of the cell.

Question 4

What can pass throug the bi-layer? Why?

Answer 4

small and non polar molecules

Becaue the hydropobic tais will repel any polar substance.

Question 5

What are the four types of membrane proteins?

Answer 5

• cell recognition: identifys the cell as “self”
• receptor: receives signals from surroungings
• enzymatic: helps with biochemical relations
• transport: moves substances in and out of cell

Question 6

What is a Membrane Protein?

Answer 6

A prtein that interacs with or ar a part of biological memebranes

Question 7

What are the two types of transport proteins?

Answer 7

• channel-specific particles or ions move freely in or out of the cell
• carrier - selective interacts with only certain molecules.

Question 8

What does permeability mean?

Answer 8

movement across the cell membrane

Question 9

What is a concentration gradient?

Answer 9

one area has a higher concentration than another

Question 10

What is diffusion?

Answer 10

movement of a substance down their concentration gradient

Question 11

What is equilibrium?

Answer 11

balanced on both sides

Question 12

What is Passive Transport?

Answer 12

no energy required aka diffusion

Question 13

What are the two types of passive transport? explain.

Answer 13

• facilitated diffusion: movement through channel proteins down a concentration gradient.
• osmosis: water diffusing across the cell membrane (need channel protein.)

Question 14

What is Hypertonic?

Answer 14

low concerntration of water outside of the cell and a higher concentration of solute.

So water moves out of the cell causing it to shrink

Question 15

What is Hypotonic?

Answer 15

a high concentration of water outside of the cell and a lower concentration of solute.

So water moves in of the cell causing it to swell

Question 16

What is Isotonic?

Answer 16

equal solute concentration and water moves in and out at equal rates.

Question 17

What is active transport?

Answer 17

when a substance moves against its concentration gradient. this required a carrier protein and ATP

Question 18

What do carrier proteins act as?

Answer 18

pumps

Question 19

What are vesicles?

Answer 19

they import and export very large molecules that can’t cross the cell membrane.

Question 20

What are the types of vesicles?

Answer 20

• exocytosis
• entocytosis
  
  • phagocytosis
  • pinocytosis

Question 21

What is exocytosis?

Answer 21

• secretion
• vesicles fuse to the cell membrane and then releases their particles
• thereby extending the cell wall

Question 22

What is endocytosis?

Answer 22

a portion of the cell membrane pinches off to format vesicle

Question 23

What is phagocytosis?

Answer 23

large substances like viruses or white blood cells

Question 24

What is pinocytosis?

Answer 24

liquid of small substances

- loss of membrane balanced by exocytosis

Question 25

What is receptor-mediated endocytosis?

Answer 25

molecules must bind to specific receptor proteins in order for vesicles to for and enter the cell.

Question 26

What are the two purposes of DNA replication?

Answer 26

- growth | - repair

Question 27

What are the four important enzymes in DNA replication? What are their functions?

Answer 27

- DNA helicase: unzips parent strand - DNA primase: creates a stating spot for polymerase - DNA polymerase: bonds new nucleotides - DNA ligase: contents Okazaki fragments and proof reads.

Question 28

What is semi-conservative replication?

Answer 28

each daughter strand contains one new strand and one parent strand.

Question 29

Which way do enzymes work? (regarding DNA) | How does this relate to Okazaki fragments

Answer 29

5' to 3' - the primase has to connect in several spots so the polymerase can work 5' to 3' even though the lagging strand's new chain is 3' to 5'

Question 30

Describe what the cell growth cycle looks like.

Answer 30

- growth one - rest/ chcekpoint (if the cell is not working properly the cell will be told to commit suicide) - growth two - rest/ checkpoint two - prophase - mitosis (PMATC)

Question 31

What is a Gene?

Answer 31

a segment of DNA that specifies the amino acid sequence of a polypeptide

Question 32

Is DNA directly in control of protein synthesis? Explain.

Answer 32

No. its code is copied into RNA and then taken out of the nucleus.

Question 33

What are the three classes of RNA? What are their functions?

Answer 33

- mRNA: takes a message from DNA to the ribosomes - rRNA: makes up ribosomes (along with proteins) mRNA slots into it. - tRNA: carries amino acid to ribosomes.

Question 34

What is Transcription?

Answer 34

making mRNA from a segment of DNA (in the nucleus)

Question 35

In Transcription what are the strands involved called?

Answer 35

- sense strand: the strand being used as a template | - non-sense strand: the strand of DNA not being used.

Question 36

What are the steps in Transcription?

Answer 36

- RNA polymerase binds and unwinds the DNA strand - DNA helix is opened so complementary base pairing can occur - RNA polymerase joins new RNA nucleotides in a sequence complementary to the sense strand of the DNA - creates mRNA