Final exam chapter 4 review

Question 1

Why is it important for a gene to have a specific sequence of nucleotides?

Answer 1

Because that sequence determines how the protein functions. And we need specific proteins to do certain functions for us to live and function properly

Question 2

What is the definition of a gene?

Answer 2

A length of DNA that codes for proteins

Question 3

List the basic steps in transcription and the end product. (3 phases)

Answer 3

Phase 1:
1.The hydrogen bonds between the bases in the DNA are broken and the histone is removed from the promoter
2. The complementary DNA strand separates and RNA polymerase binds to the promoter gene

Phase 2:
1. RNA polymerase gets the complementary bases that go together with the original DNA bases.

2. At the stop signal the mRNA and the enzyme detach from the DNA strand and transcription ends

Phase 3:
1. The original DNA strands get back together

2. 1. RNA processes the newly transcribed mRNA and removes the introns and combines the exons.
3. Then the mRNA leaves

Question 4

List the basic steps in translation and the end product. (3 phases)

Answer 4

Phase 1 Initiation:
1. mRNA returns to the cytoplasm and binds to a ribosome
2. the ribosome reads the mRNA until it hits AUG (the start codon)
3. the tRNA anticodon UAC binds to the start codon
4. The P site in the ribosome is where the polypeptide building begins

Phase 2 Elongation:
1. Then another tRNA comes and brings more amino acids to the A site in the ribosomes

2. Then the tRNA goes into the E site and exits the ribosome and is then able to be picked up again and create another anticodon

Phase 3 Termination:
1. this is where the ribosome reaches one of the three stop codons and the ribosome detaches and leaves the mRNA.

Question 5

Where are triplets, Codons, and anticodons located?

Answer 5

Triplets- In DNA
Codons- mRNA
Anticodons- tRNA

Question 6

What is a codon?

Answer 6

3 nitrogenous bases that code for the gene (the AUG stuff)

Question 7

What is the difference between mRNA, rRNA, and tRNA and their functions?

Answer 7

mRNA- Carries the RNA template outside of the cell
rRNA- It reads the amino acids and links them together
tRNA- It delivers amino acids to the ribosomes

Question 8

What is the function of RNA polymerase?

Answer 8

reading a DNA sequence and transcribing it into an RNA sequence

Question 9

what are the three functions the Rough Endoplasmic reticulum do in respect to protein synthesis?

Answer 9

1. Posttranslational modifications on proteins
2. folding of proteins
3. Sorting of proteins

Question 10

What are the 4 benefits of using an enzyme in a chemical reaction?

Answer 10

1. Increases the rate of the reaction (makes it go faster)
2. Not changed by the reaction (can be used again
3. Doesn’t change the nature of the reaction (it could’ve occurred without it)
4. Lowers the activation energy

Question 11

What does the enzyme isomerases do..?

Answer 11

It rearranges the atoms in a molecule

Question 12

What does the enzyme hydrolase do? Name an example

Answer 12

It promotes hydrolysis

Example: adding water to sucrose to make glucose and fructose

Question 13

What does the enzyme kinase do?

Answer 13

Adds a phosphate group

Question 14

Why are kinases and phosphatases so important?

Answer 14

Because they act as the on and off switch for molecules. When kinases add a phosphate group it turns them on and activates them. But when phosphatases remove the phosphate group. Then it turns them off and shuts them down.

Question 15

What is a zymogen and why are they important?

Answer 15

It is essentially an inactive enzyme that is activated when needed. A masking sequence stops the active site from being able to be seen and used.

IT is important because they keep the enzyme contained and prevent them from damaging other cells

Question 16

What is an isozyme?

Answer 16

Where there are sugars that have the same chemical formula but they need different sugars to work on them and break them down

Question 17

What does phosphatase do?

Answer 17

It removes phosphate groups

Question 18

How does glucose remain in a cell against its gradient; what enzyme is responsible

Answer 18

It gets phosphorylated to create glucose-6-phosphate so it can’t go against the gradient. The enzyme responsible is Hexokinase

Question 19

What is the purpose of the complexes in the electron transport chain?

Answer 19

When they move the electrons it makes energy. It then creates a proton gradient and pumps the free hydrogens in the cell to the outside of the cell. (complex 1,3, 4 and ATP synthase pump them across)

Question 20

What is the basic steps of the citric acid cycle?

Answer 20

Pyruvate goes into citric acid cycle and converts to acetyl coA and binds with oxalacetate which makes citrate so we can continue to use it for energy

Question 21

What is the purpose of NAD+ and NADH?

Answer 21

NAD+: to collect a hydrogen ion and take it to the electron transport chain (converts to NADH)

NADH: Goes to the electron transport chain to give proteins energy to make the Hydrogen gradient

Question 22

What is the H+ gradient important?

Answer 22

To make energy to fuel ATP synthase

Question 23

What does the enzyme Synthase do? Name an example

Answer 23

catalyzes synthesis reactions

Example: Synthase takes ADP and adds P to make ATP

Question 24

How is ATP made during oxidative phosphorylation; what enzyme is responsible?

Answer 24

The ATP has a channel for the hydrogens to go with its gradient. Which then it gives the ATP synthase to phosphorylate and make ATP.

ATP SYNTHASE IS THE ENZYME RESPONISIBLE