Molecular biochemistry W6

Question 1

What is the meaning of the term gene expression

Answer 1

The process where a gene is turned into a functional product, which could either be a protien or RNA

Question 2

What does monocistronic mRNA carry

Answer 2

• Info for one protein

Question 3

What does polycistronic mRNA carry

Answer 3

Info for multiple proteins

Question 4

What is an Operon

Answer 4

It is a cluster of genes under one promotor, transcribed as one mRNA molecule

Question 5

Why are operons polycistronic

Answer 5

As they produce multiple proteins from a single mRNA

Question 6

What is an Operator

Answer 6

A DNA sequence betwen the promtor and genes

Question 7

What is the function of an Operator

Answer 7

It inhibits transcription when bound to a repressor

Question 8

What is the repressor produced from + function

Answer 8

• It is produced from a regulatory gene
  -It prevents transcritpion of the operon when bound to the operator

Question 9

What is LAC operon

Answer 9

A well studied operon that metabloises existing lactose

Question 10

What does Lac Operon contain + why

Answer 10

• It contains a promoter, operator and genes for enxymes that metabolise lactose

Question 11

When no lactose is present is the Lac Operon active or inactive

Answer 11

Inactive

Question 12

Why is the Lac Operon inactive when there is no lactose

Answer 12

Due to the lac repressor bining to the operator

Question 13

When there is glucose and lactose is the Lac operon active or inactive

Answer 13

-Active

Question 14

Where are Operons found

Answer 14

IN Prokaryotes

Question 15

What is the function of trp Operon

Answer 15

It synthesizes tryptophan when it is absent or low

Question 16

Explain the function of the repressor when tryptophan levels are high

Answer 16

• The repressor binds to the operator and block transcription

Question 17

What happens to the represson when tryptophan is absent

Answer 17

It is removed

Question 18

Name the 2 forms chromatin exists as

Answer 18

euchromatin
heterochromatim

Question 19

Explain euchromatin and heterochromatin

Answer 19

Euchormatin: Transcriptonallya active, loosely packed
Heterochromatin:
- Transcriptionallly inactive and densely packed

Question 20

When can chromsomes only be visualised

Answer 20

• During mitosis

Question 21

What are telomeres

Answer 21

They are repetitive nucleotode sequences that protect chromosome ends from deterioration

Question 22

What are promoters + where are they located

Answer 22

DNA regions that initiate gene transcritpion
-Located upstream of the gene

Question 23

Wht are enhancers

Answer 23

Sequences that modulate gene expresiion

Question 24

What do epigenetic changes affect

Answer 24

Affect gene expression without altering DNA sequences

Question 25

Explain what happens in histone acetylation

Answer 25

- An acetyl group is added to Lysine residues , which weakens the DNA histone interaction, making DNA more accessible

Question 26

In eukaryotes what do general transcription factors bind to

Answer 26

- Promoters

Question 27

What is combinatorial control

Answer 27

When multiple transcription regulators coordinate to control on gene expression

Question 28

Where are Cis-regulatory Elements found

Answer 28

They are found on the same DNA molecule as the gene they regukate

Question 29

Where are trans regulatory elements found

Answer 29

- Distant/away from the gene they transcribe

Question 30

What are regulatory regions

Answer 30

- They are regions that detrmine gene expression based on time, conditions

Question 31

How can eukaryotic transcription regulators act across long stretches of DNA

Answer 31

- By looping intervening DNA

Question 32

What do specific transcrition factors bind to

Answer 32

ENhancer regions

Question 33

What are constitutive genes

Answer 33

- Genes that are always on

Question 34

What are facultative genes

Answer 34

- Genes that are activated only when needed for specific functions

Question 35

What is a Homeobox

Answer 35

A DNA sequence that regulates large-scale anatomical features during early embryonic development

Question 36

What does a homeobox encode

Answer 36

- Homedomain proteins, which regulate gene expression and cell differentiation

Question 37

What 2 pathways add glucose to the blood during fasting

Answer 37

- Glycogenolysis -glucpneogenesis

Question 38

What is the key enzyme in gluconeogenesis

Answer 38

- PEPCK

Question 39

What is the enzyme PEPCK regulated by

Answer 39

glucagon + corticol

Question 40

What is the open reading frame

Answer 40

The sequence that can be translated itno a protein

Question 41

What is immunohistochemistry

Answer 41

A method used to detect the target antigen directly

Question 42

What happens in direct IHC

Answer 42

When One antibody detects the target antigen directly

Question 43

What happems in indirect IHC

Answer 43

2 antibodies are used , one to detect the target antigen adn one to stect the first antibodyyy