gene expression - extra

Question 1

What is a gene?

Answer 1

A gene is a segment of DNA that codes for a specific protein or functional RNA, determining a particular trait or function in an organism

Question 2

What is a genome?

Answer 2

A genome is the complete set of an organism’s DNA, including all of its genes and noncoding sequences

Question 3

Define exons

Answer 3

Exons are the coding regions of a gene that contain the information needed to produce a protein. During RNA processing, exons are joined together after introns are removed to form the final mRNA strand used in translation

Question 4

Define introns?

Answer 4

Introns are non-coding sequences of DNA within a gene that are transcribed into RNA but removed during RNA processing and do not code for proteins

Question 5

Define functional RNA?

Answer 5

RNA that performs a function in the cell instead of coding for proteins
- tRNA = carries amino acids to the ribosomes during protein synthesis
- rRNA = forms the core of ribosomes and catalyses proteins

Question 6

Define centromere?

Answer 6

Region where sister chromatids join and spindle fibres attach

Question 7

Define telomere?

Answer 7

Repeated DNA at chromosome ends that protects them from damage

Question 8

Protein synthesis?

Answer 8

Transcription is the process of copying a gene’s DNA sequence to produce an RNA molecule. This is carried out by the enzyme RNA polymerase, which joins RNA nucleotides together to form an mRNA strand.

During translation, the mRNA produced in transcription travels from the nucleus to a ribosome, where it guides protein synthesis. As the mRNA moves through the ribosome, tRNA molecules pair with it and bring specific amino acids, which are then linked together to form a polypeptide chain (protein).

Question 9

Define gene expression?

Answer 9

Purpose: to produce molecules that carry out the cell’s function

Regulation: gene expression can be switched on or off or adjusted to the cell’s needs

Question 10

Factors that regulate gene expression?

Answer 10

1. during transcription and translation:
   - proteins (transcription factors) bind to specific DNA sequences to increase or decrease gene expression
2. through products of other genes:
   - some gene produce proteins of RNAs that control the activity of other genes, affecting phenotypes
3. via environmental exposure:
   - environmental factors (diet, stress or toxins) can alter gene expression without changing DNA
   - twin studies show identical RNA can result in different phenotypes due to environmental influences

Question 11

HOX genes?

Answer 11

• HOX genes regulate morphology
• transcription factors that control body plan and segment identity

Question 12

SRY genes?

Answer 12

• regulate cell differentiation
• transcription factor that direct male sex cell development