Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Section 4 - Genetic information, variation and relationships between organisms: 8. DNA, genes and protein synthesis > Flashcards

Section 4 - Genetic information, variation and relationships between organisms: 8. DNA, genes and protein synthesis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a gene

A

A section of DNA that codes for a polypeptide (protein) or functional RNA (eg. mRNA, tRNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 bases in the DNA sequence

A
  • Adenine
  • Thymine
  • Cytosine
  • Guanine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why do 3 bases code for each amino acid

A

Triplet code gives 64 (4^3) possible combinations, as there are 4 possible bases.
(enough to code for the 20 naturally occurring amino acids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the features of the genetic code

A
  • Degenerate
  • Non-overlapping
  • Universal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is the genetic code described as degenerate

A

Most amino acids are coded for by more than one triplet, to limit the impact of mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why can the genetic code be described as non-overlapping

A

Each base sequence is read once, in one particular direction, where the triplets don’t overlap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why can the genetic code be describes as universal

A

Each triplet code codes for the same amino acid in all organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is always the first Amino acid coded for by a gene

A

Methionine, Start Codon AUG

Later removed if not part of the chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is DNA stored in Prokaryotes (+ in Mitochondria and chloroplast)

A

Short, circular structures (plasmid), with no associated proteins

No chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the structure of a chromosome

A
  • DNA molecule wound up and wrapped around histones (proteins)
  • DNA-Histone complex is coiled
  • Coils form loops that pack together into chromatids
  • Chromatids branch off of the centromere
    (contains only 1 DNA strand)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a homologous pair

A

A pair of chromosomes, with one from the mother, and one from the father

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Diploid number

A

Number of chromosomes in homologous pairs (Humans = 46)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an allele

A

One of a number of forms of the same gene
- One from the mother and one from the father
- Each has different base sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is RNA

A

Single stranded nucleic acid transcribed from sections of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a Codon

A

Sequence of 3 bases on the mRNA that codes for one amino acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the genome

A

The complete set of genes in a cell (including those in the mitochondria/chloroplast)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the proteome

A

The full set of proteins produced by the genome
(Complete proteome = Proteins produced by 1 type of cell under certain conditions)

18
Q

What is the structure of RNA

A

Polymer of nucleotides:
- Ribose sugar
- Organic base (AUCG)
- Phosphate group

19
Q

What is mRNA

A

Messenger RNA

20
Q

What is the function of mRNA

A

Acts as a template for protein synthesis

21
Q

What is the structure of mRNA

A
  • Long, single stranded polymer of nucleotides
  • No H bonds between nucleotides, so no folding
  • Base sequence transcribed from DNA
22
Q

What is tRNA

A

Transfer RNA

23
Q

What is the function of tRNA

A

Binds to a specific amino acid, allowing for their arrangement in the polypeptide chain, for protein synthesis

24
Q

What is the structure of tRNA

A
  • Single strand of nucleotides folded into a clover shape by H bonds
  • One end binds to a specific amino acid
  • The other end has a specific anticodon, complementary to the codon that codes for the carried amino acid
25
Q

What is the process of Protein synthesis

A
  • DNA provides ‘instructions’ in the long base sequence
  • A complementary strand of pre-mRNA is made for a section of this sequence (transcription)
  • Pre-mRNA is spliced to form mRNA
  • mRNA is used as a template, to which tRNA molecules attach, aligning their amino acids to form the polypeptide chain (Translation)
26
Q

How is protein synthesis different in prokaryotes and eukaryotes

A

Prokaryotes directly transcribe mRNA form the DNA, whereas eukaryotes make pre-mRNA first, which needs to be spliced

27
Q

What is transcription

A

The formation of pre-mRNA from the DNA base sequence

28
Q

Where does transcription occur

A

In the Nucleus

29
Q

What is the process of transcription

A
  • The enzyme DNA helicase breaks the hydrogen bonds between the two DNA stands, exposing the nucleotides
  • Free nucleotides align with the complementary bases of the template strands
  • The Enzyme RNA polymerase moves along the strand, forming phosphodiester bonds between the loose nucleotides
  • DNA strands re-join after the free nucleotides are joined together)
  • When the RNA polymerase reaches a terminal sequence on the DNA, it detaches, releasing the pre-mRNA
30
Q

What is the function of DNA helicase in transcription

A

Breaks the H bonds between the two strands of DNA, exposing the bases

31
Q

What is the function of RNA polymerase in transcription

A

Moves along the strand of free nucleotides, forming phosphodiester bonds between them

32
Q

How many DNA bases are exposed at the same time during transcription

A

~12, as the double helix re-attaches together after the RNA polymerase moves past

33
Q

What is RNA splicing

A

The process that forms mRNA from pre-mRNA, to be used in translation

34
Q

Where does RNA splicing occur

A

In the Nucleus

35
Q

What are the non-coding sections of DNA

A

Introns

36
Q

What are the sections of DNA that code for polypeptides

A

Exons

37
Q

What is the process of splicing

A

The non-coding introns are spliced out by the enzyme Spliceosome, and the exons join together to form the mRNA

38
Q

What is alternative splicing

A

When the exons re-join in a different order, so the same gene can code for multiple proteins, as this gives a different mRNA base sequence

39
Q

What is translation

A

The formation of a polypeptide from mRNA

40
Q

Where in the cell does translation occur

A

In the ribosomes

41
Q

What is the process of Translation

A
  • Ribosome attaches to the start codon at one end of the mRNA
  • tRNA molecule with the complementary anticodon moves into the ribosome, carrying the specific amino acid
  • The tRNA binds to the mRNA, positioning the amino acid in the correct location in the polypeptide
  • A second tRNA moves into the ribosome, carrying the next amino acid, and attaches to the mRNA
  • A peptide bond forms between the two amino acids the bond between the first tRNA and the mRNA is broken
  • Ribosome moves along the the RNA to the next codon, repeating the process with two triplet codes within at any time
  • Synthesis continues until a stop codon is reached, when the polypeptide is released to begin folding into a protein
42
Q

What is the start codon

A

AUG - codes for Methionine

Biology (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions