Chapter 10: Gene Expression, Transcription & Translation Flashcards by Maya Velazquez

What are the 2 key processes of gene expression?

Ch 10.1

1) Transcription
2) Translation

Ch 10.1

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What is transcription?

Ch 10.1

The synthesis of RNA from a DNA template (produces an RNA copy of a gene)

Ch 10.1

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Where does Translation occur?

Ch 10.1

In the messenger RNA (mRNA)

Ch 10.1

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What happens during Translation?

Ch 10.1

a sequence of bases in an mRNA is “translated” into an amino acid sequence of a polypeptide

Ch 10.1

Gene Expression is highly accurate, which is why it utilizes a specific amino acid sequence

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What is the Central Dogma of Gene Expression?

Ch 10.1

Central Dogma: steps of principles

DNA to RNA to PROTEIN

Ch 10.1

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TRUE or FALSE: Some viruses use an RNA template instead of DNA

Ch 10.1

Template: Blueprint of nucleotide bases for replication

TRUE

Ch 10.1

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TRUE or FALSE: Information from the same DNA molecule can be used multiple times during transcription

Ch 10.2

TRUE; since transcription doesnt alter DNA, information from the same DNA molecule can be used multiple times

Ch 10.2

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Define GENE:

Ch 10.2

the Molecular Definition of a gene

A unit of nucleotide sequences of DNA that can be trancribed to RNA and produce a protein (gene expression)

Ch 10.2

Sometimes it produces more RNA instead of a protein for gene expression

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What is the function of a Promoter?

Ch 10.2

Signals the beginning of transcription

Ch 10.2

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What does the Transcribed Region contain?

Ch 10.2

Contains information that specifies a amino acid sequence

Ch 10.2

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What is the function of a Terminator?

Ch 10.2

Signals the end of transcription

Ch 10.2

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Define Regulatory Sequence

Ch 10.2

Happens before the promoter, and controls the amino acid sequences to regulate gene expression in an organism

Ch 10.2

Promoter is the beginning of transcription

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What are the 3 stages of Transcription?

Ch 10.2

1) Intiation
2) Elongation
3) Termination

Ch 10.2

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What happens during the Initiation stage of transcription?

Ch 10.2

The Initiation stage is the first stage of transcription

Happens in the promoter and functions as the recognition site, where DNA strands are separated to form an open complex

Ch 10.2

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What happens during the Elongation phase of Transcription?

Ch 10.2

RNA polymerase synthesizes RNA

Ch 10.2

Template Strand used to form Coding Strand

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Which direction is transcription synthesized?

Ch 10.2

5’ to 3’ direction

Ch 10.2

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What happens during the Termination phase of transcription?

Ch 10.2

This is the last stage of transcription

RNA polymerase reaches a terminator, releases transcription, dissociates from DNA

Ch 10.2

Terminator: Signals end of Transcription

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What is the difference between transcription in eukaryotes and prokaryotes?

Ch 10.2

Eukaryotes use extra protein

Ch 10.2

Eukaryotes have 3 forms of RNA polymerase (I, II, III) whereas bacteria have a single RNA polymerase

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A gene that contains the information for the sequence of amino acids in a polypeptide is called a __________.

10.0

a protein-encoding gene

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RNA molecules that do not code polypeptides are called…

10.0

non-coding RNAs (ncRNAs)

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During transcription, ____ is used as a template to make _______.

10.1

DNA, RNA

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During translation, the information within____ is used to make ________.

10.1

mRNA, a polypeptide

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What are the three stages of transcription?

10.2

initiation, elongation, and termination

10.2

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Label the image.

10.2

1) promoter
2) terminator
3) transcribed region
4) regulatory sequence

10.2

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During the elongation stage of transcription, nucleotides bind to the template strand and are covalently connected in which direction? | 10.2

5’ to 3’ (5 prime to 3 prime) | 10.2

Label the image. ##Footnote 10.2

1) initiation 2) elongation/synthesis of the RNA transcript 3) termination

T or F: the basic features of transcription are similar among all organisms ##Footnote 10.2

TRUE :D

A DNA template with the sequence 3’ - TACAATGTAGCC - 5’. Transcribe it into an RNA sequence reading. ##Footnote 10.2

5’ - AUGUUACAUCGG - 3’

What is the one difference between the transcription of eukaryotic genes and the transcription of bacterial genes? ##Footnotes 10.2

the transcription of eukaryotic genes tends to involve a greater number of protein components than bacterial genes

The stage of bacterial transcription in which sigma factor causes the binding of RNA polymerase to the promoter is _________. ##Footnote 10.2

initiation

Transcription of eukaryotic genes involves more _________ of protein components. ##Footnote 10.2

complexity

Before leaving the nucleus, pre mRNA transcripts are modified by splicing, as well as the addition of ______ and _____ to the ends of the mRNA. ##Footnote 10.3

caps; tails

What RNA is used during transcription present in eukaryotes? ##Footnote 10.3

pre-mRNA

What happens during splicing? ##Footnote 10.3

To become a functional mRNA, many pre-mRNAs undergo an RNA modification known as splicing, in which introns are removed and the remaining exons are connected to each other.

What are the functions of the cap? ##Footnote 10.3

1) 5’ cap is recognized by cap-binding proteins, which are needed for the proper exit of mRNAs from the nucleus 2) after an mRNA is in the cytosol, the cap structure helps to prevent its degradation 3) the cap structure is recognized by other cap-biding proteins that enable the mRNA to bind to a ribosome for translation

What is the function of a poly A tail? ##Footnote 10.3

1) aids in the export of mRNAs from the nucleus 2) stabilizes a eukaryotic mNA so that it can exist for a longer period of time in the cytosol

What complex precisely removes introns? ##Footnote 10.3

the spliceosome

What is the spliceosome composed of? ##Footnote 10.3

subunits known as snRNPs (“snurps”) that contain small nuclear RNA and a set of proteins

_____________ _____________ allows complex eukaryotes to use the same gene to make different proteins. ##Footnote 10.3

alternative splicing

Splicing occurs in 4 steps. Label the images with the correct steps. ##Footnote 10.3

1) first 2 snRNP subunits bind to the 5’ splice site and branch site 2) additional units bind to the 3’ splice site and other locations which create a spliceosome; the intron forms a loop 3) 5’ splice site is cut; the 5’ end of intron is covalently attached to the branch site and 2 snurp units are released 4) the 3’ splice site is cut; exon 1 covalently attaches to exon 2; intron loop is released with rest of snurp units and all get degraded. :D

Define the genetic code. ##Footnote 10.4

a code that specifies the relationship between the sequence of nucleotides in the condons found in mRNA and the sequence of amino acids in a polypeptide

The genetic code is read in groups of __#__ nucleotides called codons. There are __#__ different codons. 1 ___ codon; 3 _____ codons; and 61 ______. ##Footnote 10.4

1) 3 2) 64 3) start 4) stop 5) codons that specify amino acids

T or F: More than 1 codon can specify the same amino acid. ##Footnote 10.4

TRUE :)

This is a diagram of a bacterial mRNA. Label the image. ##Footnote 10.4

1) ribosomal-binding site 2) start codon 3) stop codon 4) coding sequence

What genetic code is the start codon? What about the stop codons? ##Footnote 10.4

start codon: AUG stop codons: UAA, UAG, UGA

Codons are read in a sequential and on-overlapping manner in the ______________ direction; this means it reads from right to left. ##Footnote 10.4

5’ to 3’

________ are involved in translating the nucleotide base sequence of the mRNA into the amino acid sequence of the polypeptide. ##Footnote 10.4

transfer RNA (tRNA)

The _______ in a tRNA corresponds to the amino acid that it carries. ##Footnote 10.4

anticodon

The codon 5’-GAC-3’ specifies aspartic acid. What would be the anticodon of a tRNA that recognizes this aspartic acid codon? ##Footnote 10.4

3’-CUG-5’

The reading frame of an mRNA begins with a _____ codon, and is read a series of ______ codons. ##Footnote 10.4

start; adjacent

Which two scientists discovered that synthetic RNA triplets can act like codons, causing a tRNA molecule to bind to the ribosome? ##Footnote 10.4

Nirenberg and Leder

What is the function of mRNA? ##Footnote 10.5

contains the information for the sequence of amino acids in a polypeptide according to the genetic code

What is the function of tRNA? ##Footnote 10.5

a molecule with two function sites: one (anticodon) binds to a codon in mRNA; and the second site (3’ single-stranded region) is where a specific amino acid is attached

What are translation factors? Describe the function. ##Footnote 10.5

they are proteins needed for the three stages of translation: 1) initiation factors required for assembly of mRNA, first tRNA and ribosomal units; 2) elongation factors needed to synthesize polypeptide and 3) release factors needed to recognize stop codon and disassemble translation machinery

The ribosomal subunits contain two types of macromolecules, what are they? ##Footnote 10.5

protein and RNA

What is the function of the ribosome in translation? ##Footnote 10.5

it catalyzes the formation of covalent bonds between adjacent amino acids to make a polypeptide

The structural features that are common to all species of tRNA contain what? ##Footnote 10.5

1) 2-D cloverleaf structure with 3 loops and a stem containing an anticodon 2) 3’ single-stranded region (amino acid attachment site) 3) 3-D structure involving additional folding

Cells make many different tRNAS, each encoded by a different gene OR the same gene. Which answer is correct? ##Footnote 10.5

a different gene

The enzymes that catalyze the attachment of amino acids to tRNA molecules are known as…. ##Footnote 10.5

aminoacyl-tRNA synthetases

When a tRNA has its amino acid attached, what is it called? ##Footnote 10.5

a charged tRNA

What serves as the site of translation? ##Footnote 10.5

ribosomes

Ribosomes contain 3 discrete sites where tRNA may be located. What are they called and label them on the diagram. ##Footnote 10.5

1) aminoacyl (A) site 2) peptidyl (P) site 3) exit (E) site

What amino acid is specified by the start codon? ##Footnote 10.4

methionine

Polypeptide synthesis occurs during the ____ stage of translation. ##Footnote 10.6

elongation

_______ occurs when a stop codon is reached in the mRNA. ##Footnote 10.6

termination

T or F: The 3 stop codons are recognized by a tRNA in the stage of termination. ##Footnote 10.6

FALSE; the 3 stop codons are recognized by a RELEASE FACTOR, and NOT tRNA

Where does translation occur in bacterial cells? What about eukaryotic cells? ##Footnote 10.6

cytoplasm in bacterial cells; cytosol in eukaryotic cells