Cellular Control

Question 1

What protein surrounds DNA which prevents transcription from occurring?

Answer 1

Histone

Question 2

What does a histone do?

Answer 2

Makes mRNA polymerase unable to transcribe the dna

Question 3

Why does a histone tightly wrap around a DNA molecule?

Answer 3

DNA negative
Histone positive charge
Opposites

Question 4

What are the two types of where a histone removed or prevents something?

Answer 4

Histone Acetylation
Histone Methylation

Question 5

What is histone acetylation?

Answer 5

Acetyl groups added to histone
Neutralise charge of amino acids
The amino acids detach , breaking the histone
DNA now free to be transcribed

Question 6

What is histone methylation?

Answer 6

Repressor gene activated
Methyl groups added to dna (cytosine base)and histone
Causes nucleosome to pack tightly
Causes transcription factors to not be able to bind to dna

Question 7

Name the two types of chromatin?

Answer 7

Heterochromatin
Euchromatin

Question 8

What does heterochromatin do?

Answer 8

Difficult for rna polymerase to access genus
Prevents genus being transcribed because densley packed

Question 9

What does euchromatin do?

Answer 9

Loosely packed
Easily for rna polymerase to bind to genus
Active transcription

Question 10

What does non-coding DNA do to chromatin?
What enzyme does it bind too?

Answer 10

Modifies chromatin structure
Binds to DNA methyltransferase

Question 11

What gene regulates body plan development in ALL organism?

Answer 11

Homeotic genes

Question 12

whats a homeobox gene role?

Answer 12

controls development of the body plan
ie: where limb or eye goes

also code for proteins which bind to DNA
regulate gene transcription through coding for a protein called homeodomain

Question 13

what protein does homeobox genes code for that regulates gene transcription?

Answer 13

homeodomain

Question 14

whats a hox gene?

Answer 14

only found in animals, an example of a homeobox gene
control back and front of body plan

Question 15

both hox and homeobox genes high conserved, true or false?

Answer 15

TRUE!

Question 16

what is the role of a hox gene? different to what is is!

Answer 16

produce polypeptides to control gene expression because the proteins act as transcription factors

Question 17

what is apoptosis?

Answer 17

programmed cell death in development
ie: why our fingers are not stuck together

Question 18

meiosis works with apoptosis, true or false?

Answer 18

FALSE
mitosis

Question 19

during apoptosis what would happen if there wasn’t enough cell death and what would happen if there was too much?

Answer 19

too little: tumours
too much: cell loss / degeneration

Question 20

what gene regulates apoptosis?

Answer 20

hox genes

Question 21

expression od hox genes are regulated by two things, what are they?
give examples for both

Answer 21

stimuli = internal and external

internal = damage to DNA detected in cell cycle , cell cycle pauses causes apoptosis to be triggered

external = light intensity, temperature, pathogens

Question 22

describe the process of apoptosis?

Answer 22

1. ‘bleb’ forms by cell , nucleus begins to disintegrate
2. cell fragments produced
3. cell fragments ingested and digested via phagocytic cells (digestive enzymes too)

Question 23

What’s a homeobox gene?
Role?
What do they contain?

Answer 23

Control development of body plan