TRANSCRIPTION Flashcards

1
Q

What molecules accomplish transfer of genetic info from the DNA?

A

RNA (ribonucleic acid) molecules

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2
Q

What is the process of copying DNA info into RNA called?

A
  • Transcription
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3
Q

What are the defining characteristics of DNA?

A
  • part of chromosomes, located in the nucleus
  • deoxyribose (5-carbon sugar)
  • Double Stranded
  • Nitrogenous bases: cytosine, guanine, adenine, thymine
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4
Q

What is the function of DNA?

A
  • Replicates prior to cell divison; contains info for protein synthesis
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5
Q

What are the defining characteristics of RNA?

A
  • Located in the cytoplasm
  • Ribose (5-carbon sugar_
  • Single-stranded
  • Nitrogenous bases: cytosine, guanine, adenine, uracil
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6
Q

What is the function of RNA?

A

mRNA carries DNA info to the cytoplasm and acts as a template for synthesis of protein molecules; tRNA carries amino acids to mRNA; rRNA provides structure for ribosome

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7
Q

What is mRNA?

A
  • a form of RNA that carries a gene’s info on how to build a specific polypeptide.
  • mRNA is synthesized as its nucleotides form complementary base pairs with one of the two strands of DNA that encodes a particular protein
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8
Q

What is the function of RNA polymerase in transcription of mRNA?

A
  • Recognizes the correct strand of DNA that contains the genetic message, as well as the right direction for RNA synthesis.
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9
Q

What base sequence do all mRNA molecules begin with?

A
  • AUG
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10
Q

What are the specific details of mRNA synthesis?

A
  • RNA polymerase binds to a promotor on the DNA sequence that begins a gene
  • The DNA strand unwinds and pulls apart exposing parts of the base sequence
  • RNA polymerase moves along the strand exposing other sections of the gene
  • Molecule of mRNA forms a RNA that is complementary to those along the DNA strand - they join.
  • RNA polymerase continues down the DNA strand until it reaches a special DNA base structure (termination signal)
  • This indicates that end of the gene
  • The RNA polymerase releases the newly formed mRNA molecule
  • The mRNA passes thru a pore in the nucleic envelope into the cytoplasm
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11
Q

What is the process of Translation?

A
  1. mRNA leaves the nucleus and attaches to a ribosomal subunit, forming a ribosomal complex after the second subunit attaches
  2. Translation begins as an initial tRNA anticodon recognizes it’s complementary mRNA codon at the start of a gene, and brings the first amino acid into position
  3. Translation continues as a specific tRNA molecules bring the correct amino acids to the growing polypeptide chain
  4. As the ribosome moves along the mRNA, more amino acids are added
  5. At the end of the mRNA, the ribosome releases the new polypeptide chain
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12
Q

Define genetic code

A
  • is a sequence of nucleotides on RNA molecule derived from the DNA template, that specifies the order of amino acids that makes up each protein that a cell synthesizes
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13
Q

how does RNA differ from DNA?

A

DNA is double-stranded, while RNA is single-stranded. DNA contains the base thymine, while the RNA contains the base uracil. RNA contains the sugar deoxyribose, and RNA contains the sugar, ribose

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14
Q

What is a codon?

A
  • A set of 3 nucleotides of a messenger RNA molecule that specifies a particular amino acid
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15
Q

What do tRNA molecules do?

A
  • align the specific amino acid building blocks in the proper sequence along an mRNA
  • Enables enzymes to bond them to each other
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16
Q

What are the two ends of a tRNA molecule?

A
  • Connectors that bring together the mRNA and the growing chain of amino acids
17
Q

How does tRNA pick up amino acids?

A
  • The amino acids must be activated to be picked up by tRNA
  • Special enzymes catalyze this step
  • ATP provides energy for an amino acid and its tRNA to bond
18
Q

What is an anticodon?

A
  • 3 nucleotides of a tRNA molecule that are complementary to a specific mRNA codon
19
Q

What is an “initiation codon”?

A
  • the mRNA sequence AUG specifying the amino acid methionine and the start of the encoded protein
20
Q

What is ribosomal RNA

A
  • rRNA is a type of RNA that forms part of the ribosome
21
Q

What are ribosomes role in translation?

A
  • tRNA and mRNA occur in close association with a ribosome
  • The smaller subunit of a ribosome binds to a molecule of mRNA near the first codon
  • the tRNA temporarily binds to an adjacent site on the ribosome with its amino acid
  • the ribosome moves along the mRNA adding amino acids to the extending polypeptide chain
  • The enzymatic activity necessary for bonding of the amino acids comes from ribosomal proteins and some RNA molecules
  • The larger subunit of the ribosome holds the growing chain of amino acids
22
Q

What is a polyribosome?

A
  • A group of ribosomes that form along a singular mRNA strand, that may be at different stages of formation, and can be present at any given moment
  • Several copies of the same protein
23
Q

What are “chaperones?”

A
  • Proteins that fold the polypeptide chain into a unique conformation
  • After this, it is released as a functional protein