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12 ATAR Biology > Chapter 8: Gene Expression > Flashcards

Chapter 8: Gene Expression Flashcards

1
Q

What is a genome?

A

All genetic material contained in an organism or a cell, including DNA existing as chromosomes within the nucleus, and DNA in mitochondria and chloroplasts (if present)

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2
Q

What is a gene?

A

Particular sections or organisms that carry instructions in the form of a code

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3
Q

What is polypeptide?

A

A polymer of many amino acids linked by peptide bonds; forms a protein or part of a protein (refer to figure 8.2.6 pg 156 for the process of polypeptide formation)

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4
Q

What is a codon?

A

A series of three adjacent nucleotide bases in DNA and mRNA; each codon specifies a particular amino acid to be added when a polypeptide is assembled; start and stop codons also occur

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5
Q

What is a ribosome?

A

Organelle where polypeptide synthesis occurs in all cells; locks onto mRNA molecule and moves along it to translate its code and link amino acids; formed in the nucleolus

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6
Q

What is messenger RNA (mRNA)?

A

A ribonucleic acid molecule formed in the nucleus during gene transcription; has a nitrogen base sequence complementary to DNA template segment; travels to the cytoplasm where ribosomes attach

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7
Q

What is a template strand?

A

The DNA strand that serves as a pattern for making complementary polynucleotide

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8
Q

What is transcription?

A

The formation of an mRNA molecule against the template strand of DNA molecule in the nucleus by complementary nucleotide base pairing (figure 8.2.2 pg 153 for more detail)

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9
Q

What is a non-template strand?

A

The DNA strand complementary to the template strand; does not form the pattern for the synthesis of a complementary polynucleotide

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10
Q

What is pre-mRNA?

A

An unmodified ‘immature’ mRNA molecule that contains introns

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11
Q

What are introns?

A

A section of DNA or pre-mRNA that does not code for a polypeptide; is removes (spliced) from pre-mRNA to form a mature mRNA molecule

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12
Q

What is an exon?

A

A section of DNA, pre-mRNA, or mRNA that codes for a polypeptide

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13
Q

What is mature mRNA?

A

A modified pre-mRNA molecule with introns removed; ready to move out of the nucleus to the cytoplasm

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14
Q

What is a start codon?

A

The first codon of an mRNA transcript translated by a ribosome; signals the ribosome to start translating mRNA

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15
Q

What is translation?

A

The joining of amino acids in a specific order, according to information in mRNA ‘read’ by the ribosome, to form polypeptide

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16
Q

What is transfer RNA (tRNA)?

A

An RNA molecule that picks up a particular amino acid from the cytoplasm and then pairs with a specific mRNA codon to deliver the amino acid to the growing polypeptide chain

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17
Q

What is the anticodon?

A

A sequence of three nucleotide bases on a tRNA molecule that pairs with complementary bases on an mRNA strand during translation at a ribosome

18
Q

What is the amino acid binding site?

A

The site of attachment of an amino acid to a tRNA molecule

19
Q

What is a peptide bond?

A

The bond that forms between adjacent amino acid monomers

20
Q

What is a stop codon?

A

The codon that discontinues the synthesis of the polypeptide chain

21
Q

What is coding DNA?

A

The small part of DNA used as a template for mRNA synthesis and thus for polypeptide synthesis; also known as a gene

22
Q

What is non-coding DNA?

A

All DNA sequences within the genome that are not found within mRNA-coding exons i.e. do not code for polypeptides. Many functions of non-coding DNA are yet to be determined

23
Q

What is ribosomal RNA (rRNA)?

A

A folded molecule of RNA that combines with proteins to form ribosomes; formed in the nucleolus of eukaryotic cells

24
Q

What is a telomere?

A

Hundreds of thousands of repeated short DNA sequences at the ends of chromosomes to help maintain them; short lengths lost within each replication of DNA

25
Q

What is gene expression?

A

The process in which information encoded in gene directs the production of RNA molecules (mRNA, tRNA, and rRNA) for polypeptide and thus protein synthesis

26
Q

What is gene regulation?

A

Various processes that enable a gene to be expressed (or not) in specific times and allow the proteins to be produced at required rates

27
Q

What are housekeeping genes?

A

A gene that encodes a polypeptide as part of a protein (often an enzyme) required to maintain basic cellular processes

28
Q

What are the two categories of gene regulations?

A

Short-term and long-term regulations

29
Q

What is short-term gene regulation?

A

Ensures that all of the different varieties of specialized cells can carry out their regular everyday functions

30
Q

What is long-term gene regulation?

A

determines the development of the organism through all the different life stages, including the differentiation of specialized cells

31
Q

What is a nucleosome?

A

The basic structural unit of chromatin comprising a DNA strand wrapped around a group of 8 histone molecules

32
Q

How are genes switched on and off?

A

Refer to figure 8.5.1 pg 162 for info

33
Q

What are regulatory proteins?

A

A protein that binds to DNA to switch a gene on or off

34
Q

What are transcription factors?

A

A regulatory protein whose function of to activate or inhibit transcription of coding DNA by binding to specific non-coding segments near the gene to be expressed or repressed

35
Q

What are some examples of environmental influences on gene expression?

A
  • Twins that have the same genes but have different characteristics
  • The Himalayan rabbit, the fur changes depending on the weather (darker for cooler days, white for hot days)
36
Q

What are some examples of influences on phenotypic expression that can be passed to offspring?

A
  • Arsenic
  • Heavy metals
  • Some organic pollutants
  • Lifestyle
  • Stress levels
  • Food consumed
    Can all affect how genes are expressed, which ten can be passed on to offspring
37
Q

What does epigenetics mean?

A

The study of chemical modifications to gene function that are not due to a change in the DNA sequences

38
Q

How does translation affect gene expression?

A

The mRNA is prevented from being translated into a polypeptide, so expression is switched off in that way

39
Q

What are microRNA (miRNA)

A

A small non-coding segment of RNA that plays a role in regulating gene expression at the post-transcription level

40
Q

What is morphology?

A

The shape and form of an organism or its part

41
Q

What are homeobox genes?

A

A gene of a group that cod for proteins that regulate body formation and patterning in the developing embryo (refer to figure 8.6.3 pg 167 for more detail)

42
Q

What is the most influential gene in the process of sex determination?

A

The SRY gene (sex-determining region of the Y chromosome), located on the right branch of the Y chromosomes, launches the genetic program for testes development

12 ATAR Biology (14 decks)

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