18) Cellular Control

Question 1

What does it mean by gene expression

Answer 1

determine cell structure and control cell processes/

Question 2

How can gene expression be controlled

Answer 2

transcriptional , post-transcriptional , post-transcriptional

Question 3

What are transcriptional factors

Answer 3

Control gene expression at transcriptional level.

-Proteins bind to DNA and switch it on or off by inc or dec rate of transcription.

Question 4

HOw do transcriptional factors bind in eukaryotes

Answer 4

bind to specific DNA sites near start of target gene

Question 5

How do transcriptional factors bind in prokaryotes

Answer 5

Bind to operons.

Question 6

What is an operon

Answer 6

Section of DNA that contain structural genes that are transcribed together , control elements and regulatory gene

Question 7

Describe what the control elements in a operon does

Answer 7

Structural gene - Useful proteins ,enzymes

Promoter - Part where RNA Polymerase binds to

Operator Transcriptional factors bind to

Regulatory gene code for activator or repressor

Question 8

What is the lac operon

Answer 8

Respire glucose , use lactose.

Produceenzymes needed tp respire lactose found on operon called lac operon.

Question 9

What happens in the Lac Operon ,when lactose is not present

Answer 9

Regulatory gene produces the lac repressor that binds to the operator site, when no lacatose is present.
Blocks transcriptional as RNA Polymerase can’t bind to promoter

Question 10

What happens in the Lac Operon when lactose is present

Answer 10

Lactose is present , binds to repressor, change shape so repressor can no longer bind to the Operator site.

So RNA polymerase binds to the promoter and transcription begins

Question 11

What happens when mRNA is edited at the post-transcriptional level

Answer 11

Eukaryotic DNA contain sections that don’t code amino acids - introns.

Primary mRNA transcrips contain introns and extrons

By splicing , introns are removed

mature mRNA leaves the nucleus for translation

Question 12

What is the role of cAMP

Answer 12

Activates proteins at post-transcriptional level
Activate proteins inside cells by altering their structure

Question 13

How does cAMP activate protein

Answer 13

When cAMP binds to the enzyme , changes the 3D shape and release the active subunite

Question 14

What is body plans

Answer 14

General structure of an organism

Question 15

What proteins control the body plan environmenmt

Answer 15

Hox genes

Question 16

Why are Hox Genes in all organisms helpful

Answer 16

Found in animals , plants and fungi .
Body plan development is controlleed in a similar way .

Question 17

What are homeobox genes , why is this helpful

Answer 17

Highly conserved, sequences have changed very little since evolution

Question 18

How does Hox genes control development

Answer 18

Homeobox sequences code for a part of protein called homeodomain

Homeodomain binds to specific sites on DNA - enable work as transcriptional factor

Protein bind to DNA aat start of developmental genes, activating or repressing transcription

Question 19

How is Apoptosis involved in the development of body plans

Answer 19

Programmed cell death
Enzymes insdie cell breaj down cell components in the cytoplasm
Contents break down and break up into fragments
Engulfed by phagocytes and digested

Question 20

How is Mitosis involved in the development of body plans

Answer 20

Differentiation create bulk of body parts and apoptosis refines unwanted structures.

Question 21

What internal stimuli do genes respond to

Answer 21

DNA Damage

Question 22

What external stimuli do genes respond to

Answer 22

Stress casued by lack of nutrient availabiltiy or pathogen attack

Question 23

Whaat does it mean when mutations has a neutral effect

Answer 23

Amino acid that the triplets code for doesn’t change.
Some amino acids code for by more than one triplets

Amino acidd is chemically similar to the original

Mutated triplet codes for an amino acid not involved with the protein’s function