DNA, RNA, Protein Synthesis Flashcards
Describe two differences between tRNA and mRNA
tRNA is clover leaf shape, mRNA is linear
tRNA has amino acid binding site and mRNA does not
tRNA has anticodon and mRNA has codon
How is the structure of pre-mRNA different to the mRNA used in translation?
Pre-mRNA has both exons and introns which then undergoes splicing to remove the non-coding introns leaving only exons as mRNA used in translation
Describe the structure of mRNA
A long single strand. Its base sequence is complementary to the DNA It was transcribed from.
Describe the structure of tRNA
clover leaf shape
One end is an anticodon and the opposite end is an amino acid binding site
Outline the process of transcription
DNA double helix unwinds hydrogen bonds are broken by DNA helicase.
These strands are separated and the DNA molecule uncoils exposing some of the bases
One strand is used as a template for free RNA nucleotides to lineup to their complimentary bases. It is joined by RNA polymerase.
What is RNA polymerase
Catalyses the formation of
Phosphodiester bonds between DNA bases and adjacent RNA nucleotides
Outline the process of translation
mRNA attaches itself to a ribosome.
The anticodon on tRNA attaches to complementary bases on the mRNA. Specific amino acid carried by tRNA form peptide bonds continuing to form a polypeptide chain along the codons into a stop codon is reached. this process requires ATP.
What does degenerate mean?
There is excess capacity of the DNA code. More than one triplet for each amino acid.
What is the structure of DNA?
DNA is a double helix composed of two strands of nucleotides.
What are the four nucleotide bases in DNA?
Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
True or False: RNA contains Thymine.
False. RNA contains Uracil instead of Thymine.
What is the primary function of RNA?
To act as a messenger carrying instructions from DNA for controlling the synthesis of proteins.
Fill in the blank: The process of copying DNA into RNA is called __________.
transcription.
What are the three types of RNA?
Messenger RNA (mRNA), Transfer RNA (tRNA), and Ribosomal RNA (rRNA).
What is the role of tRNA in protein synthesis?
tRNA transports amino acids to the ribosome during translation.
Which enzyme is responsible for synthesizing RNA during transcription?
RNA polymerase.
True or False: Each amino acid is coded for by a three-nucleotide sequence called a codon.
True.
What is the process of translating mRNA into a protein called?
Translation.
Fill in the blank: The sequence of nucleotides in DNA determines the sequence of __________ in proteins.
amino acids.
What is the function of ribosomes in protein synthesis?
Ribosomes make the proteins by translating the mRNA code into an amino acid sequence
What are introns?
Non-coding sequences in a gene that are removed during RNA splicing.
What is the difference between prokaryotic and eukaryotic transcription?
In prokaryotes, transcription occurs in the cytoplasm, while in eukaryotes, it occurs in the nucleus.
Fill in the blank: The process of removing introns and joining exons together is called __________.
splicing.
What is a mutation?
A random change in the DNA sequence that can lead to changes in the protein produced.
True or False: The genetic information in DNA is directly used to produce proteins.
False. It is first transcribed into RNA, which is then translated into proteins.
What is the end product of translation?
A polypeptide chain, which folds into a functional protein.
Fill in the blank: The sequence of bases in DNA is transcribed into __________ in the nucleus.
mRNA.
What are histones?
Proteins that the DNA molecule is wound around to support the DNA
What is the definition of a gene?
A sequence of DNA bases that codes for either a polypeptide or functional RNA
How does the mRNA strand end up being a complimentary copy of the DNA template strand?
Specific complimentary base pairing
What is pre-mRNA?
mRNA strands containing introns and exons
How is mature mRNA formed?
Splicing which removes intron and exons . This strand then leaves the nucleus for the second stage of protein synthesis.
How is mature mRNA formed?
Splicing which removes intron and exons . This strand then leaves the nucleus for the second stage of protein synthesis.
Describe how the DNA in a eukaryotic cell is arranged so that it can fit in the nucleus
The long molecule is wound up around HISTONES that make the molecule TIGHTLY COILED INTO COMPACT CHROMOSOMES
Differences between how DNA is arranged in eukaryotic cells and prokaryotic cells.
Prokaryotic cells not stored in nucleus when eukaryotic is
DNA in prokaryotic cells is condensed by supercooling
DNA in prokaryotic cells is not wound around histones.
How is the DNA in prokaryotic cells condensed?
Supercoiling
What is a genome?
Complete set of genes present in an organism
What is a proteome?
Complete set of proteins that a cell is able to produce
Why do prokaryotes have a higher percentage of protein-encoding DNA that humans?
Have fewer introns and have fewer multiple repeat sequences.
How could a change in amino acid sequence affect the function of an enzyme?
Polypeptide sequence changes so the shape of the enzyme changes so the substrate can’t fit into the active site and enzyme cannot catalyse reactions.
What does universal mean in the genetic code?
The same codon always codes for the same amino acid
What does non-overlapping mean in the genetic code?
Each base is only part of one codon
