Unit 1: Cells and Proteins KA 1.2: Proteins

Question 1

describe how alternative RNA splicing allows for more than one protein to be produced from one gene

Answer 1

different combinations of coding regions called exons can be left in or removed during transcription to produce different mature RNA transcripts.

this allows different proteins with different structures and functions to be produced

Question 2

the number and type of proteins produced by a cell can vary over time and are affected by various factors such as… (4)

Answer 2

-metabolic activity
-cellular stress
-in response to signalling molecules
-deseased vs healthy cells

Question 3

define the term eukatyote

Answer 3

cells which have a clearly defined nucleus

Question 4

the organelles that have membranes are… (4)

Answer 4

-endoplasmic recticulum
-golgi apparatus
-vesicles
-lysosome

Question 5

description of endoplasmic reticulium

Answer 5

-a series of membrane tubules that extend from the nuclear membrane
-rough endoplasmic reticulum: ribosomes dotted along its surface
-smooth endoplasmic reticulium: smooth surface

Question 6

description of the golgi apparatus

Answer 6

a series of flattened membrane disks that proteins pass through to be modified

Question 7

description of lysosomes

Answer 7

-membrane bound organelles that contain hydrolases which are enzymes
-these enzymes break down proteins lipids, nucleic acid and carbohydrates
-hydrolase use water to break the covalent bonds in these substances

Question 8

description of vesicles

Answer 8

membrane protein organelles that transport proteins and other substances around the cell

Question 9

describe where lipids are synthesised

Answer 9

lipids are syrhisised in the smooth endoplasmic reticulum (SER) and inserted into its membrane

Question 10

whats the difference between cytosol and cytoplasm

Answer 10

-cytosol is the fluid in which organelles are suspended
-cytoplasm includes the cytosol and all the organelles (excluding the nucleus) within the plasma membrane

Question 11

a) describe the synthesis pathway from the nucleus to cytosolic proteins

b) give some examples of cytosolic proteins

Answer 11

a) nucleus—>DNA—>gene—>mRNA—>cytosol—>cytostolic ribosome—>protein staying in the cytosol—>cystolic protein

b) protein kinases and CDKs

Question 12

a) describe the synthesis pathway from the nucleus to trans membrane proteins

b) give some examples of transmembrane proteins

Answer 12

a) nucleus—>DNA—>gene—>mRNA—>cytosol—>cytostolic ribosome—>protein attached to the membrane—>transmembrane protein

b) channels, pumps and transporters

Question 13

a) describe the synthesis pathway from the nucleus to secreted proteins

b) give some examples of secreted proteins

Answer 13

a) nucleus—>DNA—>gene—>mRNA—>cytosol—>cytostolic ribosome—>protein leaves the cell—>secreted protein

b)digestive enzyme and peptide hormones

Question 14

describe the structure of the golgi apparatus

Answer 14

the golgi apparatus is a series of flattened membrane disks that proteins can pass through to be modified (post translation modifications)

Question 15

describe how proteins move through thr golgi apparatus

Answer 15

proteins move from one disk to the next in vesicles that bud off and fuse with the next membrane

Question 16

describe the major post translational modification that occurs in the golgi

Answer 16

the addition of carbohydrates to form a glycoprotein

enzymes catalase the addition of various sugars in multiple steps to form carbohydrates