micro test 3 foreal

What is the basic building blocks of DNA and rna?

Nucleotides

Nuecleotides are made up of what?

Phosphate group, base, sugar.

Whats the difference between DNA nucleotide and rna nucleotide?

Rna has one OH in its sugar, while DNA nucleotides has an H instead.

What is the sugar in DNA nueotide called?

Deoxyribose

What is the sugar in rna nucleotide called?

Ribose

What is dTMP, where is it found, and what are its components?

Deoxy thymidine monophosphate.

Found in DNA

Made up of deoxyribose, thymine base, 1 phosphate group.

What is UMP, where is it found, and what are its components?

Uridine monophosphate,

Found in RNA

Composed of ribose sugar, uracil base, one phosphate

In base pairing, which bond is stronger? And why?

A = T

Or

G = C

G = C because it has 3 bonds instead of A = T's double bond

DNA strands are ____

Antiparallel

Why is DNA replication semiconservative?

Because each new DNA contains one old and one new strand.

What are the enzymes of dna?

Helicase, primate, DNA polymerase, and ligase.

What are the strands in DNA?

Leading and lagging.

DNA polymerase only works in which direction?

5’ - 3’

Lagging strands is what?

Fragmented

Helicase

Unwinds dna

Primase

Adds rna primer

DNA polymerase

Builds DNA (5’ - 3’)

Ligase

Seals fragments

How does DNA polymerase create the lagging strand?

DNA polymerase can only make DNA in a 5’-3' direction. Since the lagging strand is antiparallel, it must be created in fragments. Primase comes and creates rna primers which are the starting points of the dna polymerase and then begins by turning these primers into okazaki fragments. Ligase then comes in and connects and seals the fragments.

Rna primers must be

Removed and replaced with DNA before ligase seals it up.

Leading strand

Is continuous

Lagging strand

Is discontinuous (okazaki fragments)

In transcription

DNA becomes mRNA (RNA polymerase)

Rna polymerase

Binds to the prometer site of dna. Creating mRNA.

When is mRNA released in transcription?

When the rna polymerase reaches the terminator sequence.

Where does transcription occur?

Cytoplasm

In transcription, both dna strands are used

False

Silent mutation

1 base change

Silent mutation

No change

Missense mutation

Different amino acid

Nonsense mutation

Stop codon

Other word for lack operon

Inducible

Other word for trp operon

Repressible

Lac operon

Default mode is off. It can be turned on by lactose.

Trp operon

Default mode is on. Its csn be turned off with tryptophan

Inducible operon uses what substrate?

Lactose

Repressive operon uses what product?

Tryptophan

Inducible operon purpose

To make enzymes when the substrate is present.

Repressible operon purpose

To stop making the product when there’s enough.

In the lac operon, what directly causes transcription to begin?

A. Lactose binds RNA polymerase
B. Lactose activates CAP (glucose)
C. Lactose inactivates the repressor
D. Lactose binds the promoter

C. Lactose inactivates the repressor

A mutation causes the repressor protein in the trp operon to be permanently inactive. What happens?

A. Operon is always OFF
B. Operon is always ON
C. Operon turns OFF only when tryptophan is absent
D. No transcription occurs

B. Operon is always ON

Which mutation is most likely to produce a completely nonfunctional protein?

A. Silent mutation
B. Missense mutation
C. Nonsense mutation
D. Frameshift mutation

D. Frameshift mutation

In an inducible operon, transcription occurs when:

A. The repressor is active
B. The repressor is bound to DNA
C. The repressor is inactive
D. The product is abundant

A. The repressor is active

A mutation changes this codon:

AAA → UAA

What type of mutation is this?

A. Silent
B. Missense
C. Nonsense
D. Frameshift

C. Nonsense

In the lac operon, what happens if the repressor cannot bind lactose?

A. Operon always ON
B. Operon always OFF
C. Operon works normally
D. Only structural genes affected

B. Operon always OFF

Which statement is TRUE about repressible operons?

A. They are usually involved in breaking down substrates
B. They are turned on by substrates
C. They are turned off when the product accumulates
D. They are always inactive

C. They are turned off when the product accumulates

A frameshift mutation occurs early in a gene. What is the MOST likely outcome?

A. Only one amino acid changes
B. Protein is slightly altered
C. Entire downstream sequence is altered
D. No effect on protein

C. Entire downstream sequence is altered

Which scenario would result in continuous expression of the lac operon?

A. Repressor permanently active
B. Repressor cannot bind operator
C. No lactose present
D. RNA polymerase blocked

A. Repressor permanently active

Which of the following best describes a corepressor?

A. A molecule that activates transcription
B. A molecule that inactivates RNA polymerase
C. A molecule that activates the repressor
D. A molecule that binds the promoter

C. A molecule that activates the repressor

Catabolism

break down → release energy

Anabolism

build → uses energy

Active site

Binds substrate

What are factors that affect enzymes

Temperature, pH, Inhibitors.

What happens to enzymes during high heat?

Denaturizationg

Competitive inhibitor

competes for active sites

Glycolysis

Glucose turns into pyruvate to make small amount of ATP

In glycolysis, how many carbons are in glucose, and how many carbons are split into what?

Glucose has 6 carbons, and when they get split into 2 pyruvates 3 carbons each.

Result of glycolysis

2 Atp, 2 NADH, 2 pyruvate

Where does glycolysis occur?

Cytoplasm

Glycolysis requires O2?

False

Glycolysis produces the most ATP

False

State each cycle in order

Glycolysis - Krebs Cycle - ETC

Which process produces the MOST ATP?

A. Glycolysis
B. Fermentation
C. Krebs cycle
D. Electron transport chain

D. Electron transport chain

Which of the following can occur without oxygen?

A. Electron transport chain
B. Glycolysis
C. Krebs cycle
D. Oxidative phosphorylation

B. Glycolysis

What is the final electron acceptor in aerobic respiration?

A. NADH
B. Pyruvate
C. Oxygen
D. ATP

C. Oxygen

Which molecule is directly produced by glycolysis?

A. Acetyl-CoA
B. Pyruvate
C. CO₂
D. FADH₂

B. Pyruvate

Where does glycolysis occur?

A. Mitochondria
B. Cytoplasm
C. Nucleus
D. Cell membrane

B. Cytoplasm

Fermentation allows cells to:

A. Produce large amounts of ATP
B. Continue glycolysis by regenerating NAD⁺
C. Use oxygen efficiently
D. Run the Krebs cycle

B. Continue glycolysis by regenerating NAD⁺

A facultative anaerobe will:

A. Die in oxygen
B. Only use fermentation
C. Use oxygen if available but can survive without it
D. Only grow without oxygen

C. Use oxygen if available but can survive without it

Where does glycolysis occur?

A. Mitochondria
B. Cytoplasm
C. Nucleus
D. Cell membrane

B. Cytoplasm

Which pathway produces NADH and FADH₂?

A. Glycolysis
B. Fermentation
C. Krebs cycle
D. ETC

C. Krebs cycle

What happens if oxygen is NOT available?

A. ETC continues normally
B. NADH cannot be oxidized
C. Glycolysis stops immediately
D. ATP production increases

B. NADH cannot be oxidized

Which statement is TRUE about fermentation?

A. It produces more ATP than respiration
B. It uses the electron transport chain
C. It regenerates NAD⁺
D. It requires oxygen

C. It regenerates NAD⁺

Krebs Cycle

Makes NADH/FADH₂

Electron Transport Chain (ETC)

Makes MOST ATP

Obligate aerobe

Needs O2

Obligate Anaerobe

O2 kills it

Facultative anaerobe

can survive in both O2 and without O2

Fermentation

Doesn’t use ETC, Low ATP

Aerobic respiration

Uses, O2, High ATP

What are enzyme cofactors

Helpers (vitamins, metals)