Unit 3 Part 2

Question 1

Gene expression

Answer 1

Mechanism by which genetic info in a gene is expressed as a functional protein
- Functional protein like an enzyme will effect the organism’s phenotype

Question 2

What does gene expressions involve?

Answer 2

• Transcription of a gene to produce mRNA
• Translation of mRNA by ribosomes to produce a functional protein

Question 3

Phenotype

Answer 3

Observable traits that are a result of an organism’s genotype and environmental factors

Question 4

Genotype

Answer 4

The combination of alleles inherited by an organism

Question 5

How is translation regulated?

Answer 5

By promoter regions, enhancers, and transcription factors

Question 6

Where are promoter regions located?

Answer 6

Near the beginning of a gene

Question 7

RNA polymerase

Answer 7

Enzymes that transcribe genes to mRNA and attaches to promoter regions along w/ transcription factors

Question 8

Enhancers

Answer 8

Regulatory sequences of DNA

Question 9

Where are enhancers located?

Answer 9

Away from the gene

Question 10

What do transcription factors do?

Answer 10

Bind to enhancer region which interacts and activates the promoter region

Question 11

What are transcription factors?

Answer 11

Regulatory binding proteins

Question 12

What can different transcription factors do?

Answer 12

Activate or repress transcription by interacting w/ each other, other proteins, and RNA polymerase

Question 13

What do promoters, enhancers, and regulatory proteins do?

Answer 13

Allow a cell to respond to internal and external factors and control the genes that are transcribed

Question 14

How can translation be further regulated?

Answer 14

By degradation of mRna by nuclease enzymes

Question 15

How does regulation of transcription effect regulation of translation?

Answer 15

Regulation of transcription regulates the quantity of mRNA that’s produced which regulates rate of translation in a cell

Question 16

What do nucleases do?

Answer 16

Break down mRNA to RNA nucleotides which can be recycled by cell to produce new mRNA molecules

Question 17

Where are enhancers regions found?

Answer 17

Found upstream of the gene
- Before genetic sequences that are being transcribed

Question 18

What do transcription factors do?

Answer 18

Bind to promoter regions and help regulate transcription of DNA

Question 19

How long can mRNA be present in a human cells?

Answer 19

From minutes up to days before its broken down by nucleotides

Question 20

What does the cell have to do in order to stop producing the protein in question?

Answer 20

It will need to stop making new mRNA and destroy the ones already circulating inside the cell

Question 21

Epigenisis

Answer 21

Process by which a multicellular organism develops from zygote through a sequence of steps in which cells differentiate and organs form

Question 22

What is epigensis a result of?

Answer 22

interactions between genes and their environments during their developments

Question 23

Structure of mRNA

Answer 23

5’ is called the protective cap
3’ is called poly A tail

Question 24

Epigenetics

Answer 24

The study of changes in an organism caused by modification of gene expression by epigenetic tags rather than changes in genetic code
- Changes phenotype but not genotype

Question 25

Three layers of cell in a human embryo

Answer 25

1. Ectoderm - Forms tissue like skin and brain 2. Mesoderm - Forms tissues like skeleton and circulatory system 3. Endoderm - Forms tissues like lungs and liver

Question 26

Epigenetic tags

Answer 26

Chemical markers that attach to DNA or histone proteins and influence transcription of genes - Usually stay in place during mitosis or meiosis

Question 27

Genome

Answer 27

Includes all genetic info of an organism, all chromosomes, and mitochondrial and chloroplast DNA found in a cell

Question 28

What are the exception of genomes and why?

Answer 28

Red blood cells - b/c no nuclues Gamets - b/c only contain half the genetic material

Question 29

What do patters of gene expression determine?

Answer 29

How a cell differentiates

Question 30

Transcriptome

Answer 30

Refers to all RNA molecules transcribed at a specific time w/in a cellular organism

Question 31

What do transcriptomes represent

Answer 31

Active genes and their expression w/in a cell or organism

Question 32

Proteome

Answer 32

Complete set of proteins present in a cell or organism at a given time

Question 33

What is different about proteomes of different cell types in same organisms?

Answer 33

They will be different b/c gene expression depends on the cell type

Question 34

Methyl groups

Answer 34

Can act as epigenetic tags by attaching to promoter regions or histones - Can attach to amino acids or histone proteins

Question 35

What do methyl groups that are attached to cysteine nucleotides in prometer regions do?

Answer 35

Repress activity of prometer preventing gene from being transmitted

Question 36

Methylation of histone proteins

Answer 36

Can cause transcription to be repressed, by DNA binding tighter to nucleotides, or activated by unwinding DNA from nucleotides

Question 37

Epigenetic inheritance

Answer 37

beneficial as cell grows and results in daughter cells having same epigenetic tags as parent

Question 38

What is similar about parent and daughter cells?

Answer 38

Daughter cells will express some as parent cell + carry out some functions - Inherit phonotypic changes, epigenetic tags of parent cell

Question 39

Epigenome

Answer 39

Has all epigenetic tags on DNA and histone proteins

Question 40

Ex. of environment effecting epigenome

Answer 40

1. Diet - A person's diet or their mothers while pregnant alters epigenome 2. Cigarette - Epignetic changes due to exposure to cigarette smoke can lead to lung cancer 3. Air pollution - like diesel fumes, are able to add/ remove methyl epigenetic tags from an individual's epigenome - Addition/ removal of epigenetic tags changes which genes are expressed

Question 41

Removal of epigenetic tags

Answer 41

Most are removed during fertilization of egg and sperm in a process called reprogramming - A small number are not removed

Question 42

What allows gemets to be specialised cells?

Answer 42

The epigenome of the sperm and egg

Question 43

Reprogramming

Answer 43

The reprogramming of epigenome of a zygote produces stem cells

Question 44

Genomic imprinting

Answer 44

A process by which only one of the two inherited genes for a trait is expressed - One copy of the gene is silenced by epigenetic tags during egg and sperm formaion

Question 45

Monozygotic twins

Answer 45

Identical, a result of fertilization of one gene - Clones and have same genome + v similar epigenomes

Question 46

Epigenomes of monozygotic twins

Answer 46

Born with almost identical epigenomes, drastically change throughout life resulting in dif gene expression

Question 47

Factors outside the cell that impact the pattern of gene expression

Answer 47

Presence of biochemical molecules which a cell metabolizes - Gene expression in E.coli bacteria is impacted by presence/ absence of sugar lactose Many Hormones form hormone receptors complexes w/in the cytoplasm of cell - Hormone - receptors complex moves into nucleus where it binds to genes regulating transcription of DNA

Question 48

What does the Lac operon do

Answer 48

regulates the transcription of the enzymes that are required for metabolism of lactose

Question 49

What does the Lac operon consist of?

Answer 49

a promoter, an operator and a sequence of three genes

Question 50

What happens when a lactose is present?

Answer 50

It binds to the repressor protein. The repressor protein changes shape, and is released from the operator

Question 51

What happens when a lactose is absent?

Answer 51

a repressor protein binds to the operator and blocks RNA polymerase from transcribing the genes