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Mrs. Unger's AP Biology > Unit 5: Protein Synthesis > Flashcards

Unit 5: Protein Synthesis Flashcards

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1
Q

Define

Transcription

A

Using DNA as a template to make mRNA

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2
Q

Define

Translation

A

Production of polypeptides using the DNA code (copied into molecule of mRNA)

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3
Q

Explain why DNA has a template and coding strand

A

DNA has two strands; each gene is encoded on only one, while the other helps stabilize the molecule and make mRNA

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4
Q

Compare the template and coding strands

A
  • *Coding**: Carries the information for making the gene product
  • *Template**: Complementary to the coding strand; is used to make the mRNA
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5
Q

The mRNA sequence most resembles…

A

The coding strand

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6
Q

Outline the process of

Transcription: Initiation (Euks)

A
  1. Specific transcription factors bind to the promoter
  2. RNA Polymerase binds to the promoter
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7
Q

Define

Promoter

A

A segment of DNA before a gene which is the “docking area” for RNA polymerase to bind

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8
Q

Define

Transcription factors

A

Proteins that bind to the promoter and can either increase or decrease the RNA polymerases’ ability to bind

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9
Q

Outline the process of

Transcription: Elongation

A

RNA polymerase separates the DNA and adds complementary base pairs to the template strand

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10
Q

Define

RNA polymerase

A

The enzyme used during transcription to make mRNA

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11
Q

In which direction is mRNA made?

A

5’ to 3’

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12
Q

Importance of

5’ cap

A

A chemical modification to the 5’ end of mRNA that is being formed, which prevents nuclear enzymes from breaking down the mRNA as it is being made

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13
Q

Outline the process of

Transcription: Termination

A

RNA polymerase reaches terminator sequence on DNA, causing the DNA, polymerase, and mRNA to dissociate

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14
Q

Importance of

Poly-A tail

A

Sequence of many adenines that is added after eukaryotic transcription is complete, which allows the mRNA to exit the nucleus

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15
Q

List

Eukaryotic modifications to mRNA

A
  1. 5’ cap
  2. Poly-A tail
  3. Splicing
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16
Q

Define

Exon

A

Segments of a gene that are expressed

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17
Q

Define

Intron

A

Segments of a gene that are not expressed; must be spliced out to make functional gene product

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18
Q

Define

Splicing

A

Removal of introns and re-joining of eons to make a mature mRNA

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19
Q

What is alternative splicing?

A

Some genes contain multiple exons, which can be rearranged in different ways to produce multiple unique proteins from the same gene (WHAT?! SO COOL!)

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20
Q

Compare

Transcription in Proks vs. Euks

A
  • Prokaryotes have one promoter that controls multiple related genes, which may be regulated by an operon
  • Related functional genes may be on different chromosomes in eukaryotes but may be regulated by transcription factors so their production is coordinated
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21
Q

Define

Operon

A

In prokaryotes ONLY
A segment of the genome that has one promoter, an operator, and several functionally related genes

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22
Q

Define

Operator

A

Part of the prokaryotic operon that can bind to a repressor or inducer, like a “switch” to control transcription

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23
Q

Define

Stem cell

A

In multicellular eukaryotes, cells that are undifferentiated
Can divide to produce cell types that are different by changing gene expression

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24
Q

Define

Differentiation

A

When stem cells divide, the daughter cells may turn off specific genes (based on cell signaling) and express only tissue-specific genes
Largely controlled by which transcription factors are present or made

25
Q

Define

Epigenetics

A

Modifications to gene expression without modifying the DNA sequence

26
Q

Examples of

Epigenetic control

A

DNA methylation (prevents RNA polymerase from binding) Histone modification (histones may tighten and become less accessible or loosen and become more accessible)

27
Q

Why is transcription regulated?

A

Once mRNA is produced, translation isn’t as highly regulated. Regulating transcription ensures only the genes that the cell needs are expressed and prevents wasting material on unnecessary genes.

28
Q

Define

The lac operon

A

In prokaryotes, several genes control for the ability to use lactose for ATP production. They are all controlled by a single operator.

29
Q

What happens to the lac operon when lactose is absent?

A

The lac operator has a repressor bound, which prevents production of the associated genes

30
Q

What happens to the lac operon when lactose is present?

A

Allolactose (isomer of lactose) binds to the lac repressor and prevents it from binding to the operator. RNA Polymerase can then move past the operator to express the lac genes

31
Q

Describe

tRNA

A

A single strand of RNA which loops back onto itself. At one end there is a region that binds an amino acid. At the other end of the folded RNA there is an area that contains a unique sequence of nucleotides, called the anticodon

32
Q

How many tRNAs are there? Why?

A

64, each with a unique anticodon (anticodon = 3 nucleotides, each of which can be either A, U, C, or G) making 43 possible anticodons

33
Q

How many amino acids are there?

A

About 20

34
Q

Define

The genetic code

A

The specific amino acid coded for by each possible codon

35
Q

The genetic code is considered…

A
  1. Nearly universal and 2. Redundant
36
Q

What determines the genetic code?

A

The enzyme that joins the amino acid and tRNA (called aminoacyl tRNA synthetase, which you don’t have to know but is still impressive). Changes to this enzyme will change which amino acid the tRNA brings to the ribosome

37
Q

Describe

Ribosomal structure

A

Two subunits, each made of proteins and RNA (called ribosomal RNA).
The small subunit is smaller.
The large subunit is larger.
Eukaryotic large and small ribosomal subunits are larger than the ribosomal subunits found in prokaryotes (and in mitochondria and chloroplasts)

38
Q

Describe

Translation: Initiation

A
  • Small ribosomal subunit binds to the 5’ end of mRNA
  • Subunit reads mRNA sequences until it finds an A-U-G
  • tRNA with the anticodon U-A-C joins; This particular tRNA carries the amino acid methionine
  • A large ribosomal subunit binds to the small ribosomal subunit/tRNA/mRNA combination
39
Q

Define

Codon

A

Three nucleotide bases on mRNA

40
Q

Describe

Translation: Elongation

A
  • tRNA brings amino acid to ribosome (determined by the mRNA codon being complementary to the tRNA anticodon)
  • Peptide bond forms between the new amino acid and the growing polypeptide
  • tRNA (without amino acid) leaves ribosome
41
Q

Describe

Translation: Termination

A
  • Ribosome continues along mRNA until a stop codon is reached
  • Release factors bind
  • mRNA, tRNAs, polypeptide, and ribosomal subunits all dissociate
42
Q

List

Three types of substitution mutation

A

Nonsense

Missense

Silent

43
Q

Describe

Nonsense mutation

A

A change to DNA that results in an mRNA coding for a stop codon instead of an amino acid

44
Q

Describe

Missense mutation

A

A change to DNA that results in an mRNA coding for a different amino acid

45
Q

Describe

Silent mutation

A

A change to DNA that results in an mRNA coding for the same amino acid as the original DNA

46
Q

What causes

Frameshift mutations

A

Insertion or deletion of nucleotides (not in multiples of 3)

47
Q

Describe

Frameshift mutations

A

A change in DNA that results in an mRNA whose reading frame differs from the original. All downstream amino acids are affected.

Ex:

Normal: “THE FAT CAT RAN”

Mutated (delete E): “THF ATC ATR AN”

48
Q

In which direction are polypeptides made?

A

N terminus to C terminus
Backbone: NH2-C-C-…..-N-C-COOH

49
Q

Define

Mutagen

A

Any agent that causes changes to DNA

50
Q

List

Mutagens

A

Certain chemicals (carcinogens), radiation, certain viruses

51
Q

Define

Biotechnology

A

The intentional use of biological processes for other purposes

52
Q

Purpose of

PCR

A

Polymerase chain reaction; makes multiple copies of a segment of DNA

53
Q

Outline the process of

PCR

A
  1. DNA is heated to separate strands
  2. Primers are added, which bind to each side of the DNA segment of interest
  3. DNA polymerases are added, which replicates DNA strand
  4. Repeated cycles of heating and cooling each double the amount of DNA present
54
Q

Purpose of

Gel electrophoresis

A

Separate DNA segments by length

55
Q

Uses of

Gel electrophoresis

A

DNA profiling, paternity testing

56
Q

Outline

Genetic modification

A
  1. A gene from one organism (donor) is inserted into the embryo of another organism (recipient).
  2. The gene of interest from the donor is combined with a functional promoter from the recipient.
  3. This is then inserted into the genome. If expressed, the recipient is transgenic.
57
Q

Define

GMO

A

Genetically modified organism; an organism whose genes were modified for human benefit.

58
Q

Examples of

GMOs

A
  • Genetically modified plants: Insect-resistant crops; pesticide resistant crops; Nutrient fortified crops.
  • GM animals: Glofish; pharmaceutical-milking animals;
  • GM bacteria for the production of pharmaceuticals, vaccines, antibodies, etc

Mrs. Unger's AP Biology (16 decks)

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