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Biology > Unit 3 Part 2 > Flashcards

Unit 3 Part 2 Flashcards

D2.2 Gene Expression

1
Q

Gene expression

A

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

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2
Q

What does gene expressions involve?

A
  • Transcription of a gene to produce mRNA
  • Translation of mRNA by ribosomes to produce a functional protein
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3
Q

Phenotype

A

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

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4
Q

Genotype

A

The combination of alleles inherited by an organism

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5
Q

How is translation regulated?

A

By promoter regions, enhancers, and transcription factors

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6
Q

Where are promoter regions located?

A

Near the beginning of a gene

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7
Q

RNA polymerase

A

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

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8
Q

Enhancers

A

Regulatory sequences of DNA

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9
Q

Where are enhancers located?

A

Away from the gene

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10
Q

What do transcription factors do?

A

Bind to enhancer region which interacts and activates the promoter region

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11
Q

What are transcription factors?

A

Regulatory binding proteins

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12
Q

What can different transcription factors do?

A

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

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13
Q

What do promoters, enhancers, and regulatory proteins do?

A

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

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14
Q

How can translation be further regulated?

A

By degradation of mRna by nuclease enzymes

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15
Q

How does regulation of transcription effect regulation of translation?

A

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

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16
Q

What do nucleases do?

A

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

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17
Q

Where are enhancers regions found?

A

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

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18
Q

What do transcription factors do?

A

Bind to promoter regions and help regulate transcription of DNA

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19
Q

How long can mRNA be present in a human cells?

A

From minutes up to days before its broken down by nucleotides

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20
Q

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

A

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

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21
Q

Epigenisis

A

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

22
Q

What is epigensis a result of?

A

interactions between genes and their environments during their developments

23
Q

Structure of mRNA

A

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

24
Q

Epigenetics

A

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

25
Q

Three layers of cell in a human embryo

A
  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
26
Q

Epigenetic tags

A

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

27
Q

Genome

A

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

28
Q

What are the exception of genomes and why?

A

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

29
Q

What do patters of gene expression determine?

A

How a cell differentiates

30
Q

Transcriptome

A

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

31
Q

What do transcriptomes represent

A

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

32
Q

Proteome

A

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

33
Q

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

A

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

34
Q

Methyl groups

A

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

35
Q

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

A

Repress activity of prometer preventing gene from being transmitted

36
Q

Methylation of histone proteins

A

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

37
Q

Epigenetic inheritance

A

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

38
Q

What is similar about parent and daughter cells?

A

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

39
Q

Epigenome

A

Has all epigenetic tags on DNA and histone proteins

40
Q

Ex. of environment effecting epigenome

A
  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
41
Q

Removal of epigenetic tags

A

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

42
Q

What allows gemets to be specialised cells?

A

The epigenome of the sperm and egg

43
Q

Reprogramming

A

The reprogramming of epigenome of a zygote produces stem cells

44
Q

Genomic imprinting

A

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

45
Q

Monozygotic twins

A

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

46
Q

Epigenomes of monozygotic twins

A

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

47
Q

Factors outside the cell that impact the pattern of gene expression

A

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

48
Q

What does the Lac operon do

A

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

49
Q

What does the Lac operon consist of?

A

a promoter, an operator and a sequence of three genes

50
Q

What happens when a lactose is present?

A

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

51
Q

What happens when a lactose is absent?

A

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

Biology (22 decks)

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