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BIOLOGY STAGE 2 RATGANG > TOPIC 1.2 DNA AND PROTEIN SYNTHESIS [completed] > Flashcards

TOPIC 1.2 DNA AND PROTEIN SYNTHESIS [completed] Flashcards

1
Q

What are the structure and function of genes?

A

A gene consists of a unique sequence of DNA nucleotides that code an RNA molecule. Genes control specific characteristics and are located at specific points on a particular chromosome.

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2
Q

What is a genome?

A

Genome is a term used to describe the total number of genes of an organism

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3
Q

A genome can be divided into two types of DNA, what are they?

A

The genomes can be divided into coding and non-coding DNA. Called EXONS (coding DNA) and INTRONS (Non-coding DNA)

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4
Q

What is the function of EXONS?

A

Exons are the coding sequences of DNA that is translated into polypeptides/proteins

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5
Q

What is the function of INTRONS?

A

Introns are the non-coding sections of the DNA and do not code for polypeptides/proteins.
- Introns can be transcribed into RNA molecules, such as RNA (rRNA), transfer RNA and micro RNA.

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6
Q

What is RNA

A

Ribonucleic acids (RNA) molecules are made up of repeating units called nucleotides. And are essential in the expression and regulation of genes.

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7
Q

What is the difference between DNA AND RNA

A

> a pentose (or 5-carbon) sugar called ribose

> a phosphate group,

> one of four organic bases: adenine (A), cytosine (c), guanine (G) and uracil (U)

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8
Q

What happens during RNA synthesis?

A

When RNA molecules are synthesised, the RNA nucleotides will temporarily bond with their complementary base on the template strand of the DNA molecule.
> Adenine only bonds to Uracil with two hydrogen bonds forming (A=U).
> Guanine only bonds to Cytosine with three hydrogen bonds forming (C≡G

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9
Q

What are the 4 major types of RNA?

A

There are four major types of RNA
> messenger RNA (mRNA)
> transfer RNA (tRNA)
> ribosomal RNA (rRNA)
> micro RNA (miRNA)

they are all single stranded:

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10
Q

Explain how introns and exons are involved in RNA Splicing?

A

genes consist of both introns and exons, the introns must be spliced out of the pre-mRNA forming mature mRNA before being translated into the amino acid sequence (RNA SPLICING)

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11
Q

what is RNA splicing?

A

RNA splicing and it ensures the synthesis of the correct sequence of amino acids, and hence protein.

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12
Q

What is the structure of DNA?

A

> is a double helix molecule consisting of two strands of nucleotide building blocks

> has four organic bases: adenine, thymine, guanine, and cytosine

> has two strands that are complementary to each other.

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13
Q

How is DNA read?

A

> is directional and read 5’ to 3’.*contains genes that are hereditary units.

> has one strand that can act as a template and a second non-coding template strand (not directly involved in mRNA synthesis)

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14
Q

Describe the bonds between the base pairs

A

(A=T and C≡G). and joined by weak hydrogen bonds

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15
Q

Name the 4 different types of RNA

A

> mRNA (Messenger RNA)
tRNA (Trandfers RNA)
rRNA (Ribosomal RNA)
miRNA (Micro RNA)

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16
Q

How is mRNA involved in transcription?

A

mRNA is synthesised using DNA as a template in transcription.

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17
Q

Where does mRNA synthesis take place?

A

> nucleus of cells
After transcription it becomes mature mRNA,
moves to the cytosol

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18
Q

What is the structure of mRNA?

A

mRNA is a single-stranded molecule consisting of a sequence of RNA nucleotides

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19
Q

What is the function of mRNA?

A

mRNA codes for a specific sequence of amino acids called an RNA codon [three base sequence]

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20
Q

What is the structure of tRNA?

A

> it contains an anticodon, which is three bases that are complementary to an mRNA codon.

> tRNA also carries a specific amino acid at the opposite end to the anticodon.

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21
Q

What is the function of tRNA?

A

Function of a tRNA molecule is to place a specific amino acid into its correct sequence in the polypeptide being synthesised.

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22
Q

What happens after the tRNA transfers the specific amino acid?

A

it can collect another corresponding amino acid in the cytosol to add to the polypeptide chain.

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23
Q

How do tRNA and the amino acids attach to each other?

A

The attachment of an amino acid to a tRNA molecule involves enzymes that have specific shapes to ensure each of the 20 amino acids are only ever attached to their corresponding tRNA(s).

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24
Q

What is rRNA?

A

> Ribosomes are made up of ribosomal RNA (rRNA).
Ribosomes are the sites of translation during protein synthesis.

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25
Q

How are ribosomes involved in translation?

A

Ribosomes move along the mRNA strand ranslating the mRNA code into a sequence of amino acids, called a polypeptide molecule

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26
Q

What is MiRNA

A

Micro RNA are small non-coding RNA molecules consisting of approximately 22 nucleotides.
> regulating gene expression after transcription has occurred.

27
Q

What is the function of miRNA?

A

They exert gene regulation by binding to a small section of a specific messenger RNA (mRNA) molecule, preventing it from being translated.

28
Q

What are amino acids?

A

are the building blocks of polypeptides and protein molecules.

29
Q

What are polypeptides?

A

A polypeptide is a sequence of amino acids linked together by strong peptide bonds

30
Q

What two DNA strands does DNA consist of?

A

> The coding (non-template) strand
The template strand

31
Q

What is the non-template coding strand?

A

It determines the correct mRNA sequence, doesn’t directly take part in transcription

EXAMPLE TO HELP REMEMBER
the mRNA produced from transcription will have the same code as the coding strand, except T is replaced with U

32
Q

What is the template strand?

A

complementary to the coding strand and provides the template genetic code for a growing mRNA strand to form against.

EXAMPLE TO HELP REMEMBER
i.e. mRNA produced is complementary to the template strand, except T is replaced with U

33
Q

What does the coding strand consist of?

A

triplets of bases called DNA codons.

34
Q

What does the template strand consist of?

A

As the template strand is complementary to the coding strand it consists of triplets of bases called DNA anticodons.

35
Q

What happens to mRNA during transcription?

A

molecules are synthesised against the template strand in a complementary fashion and therefore consist of mRNA codons.

> correspond with the coding strands DNA codons).

36
Q

What occurs to the mRNA codons in transcription?

A

tRNA molecules with complementary anticodons to the mRNA codons bring specific amino acids to the growing polypeptide chain.

37
Q

What are codons?

A

Triplets of bases are the smallest units necessary to code for all 20 amino acids.

Example
GCG UGG UGU

38
Q

How does mRNA translate codons into amino acids?

A

mRNA molecules transmit a copy of a gene from the coding strand, from the nucleus to the ribosomes, where the sequence of codons is translated into amino acids.

39
Q

What is transcription?

A

occurs in the nucleus, the mRNA molecule is synthesised from a gene in the DNA.

> genetic code is transcribed or re-written from DNA into mRNA.

40
Q

What is the process of transcription?

A

enzyme RNA polymerase separating the two strands of DNA

> combines RNA nucleotides together in the 5’ to 3’ direction, along the DNA template strand

41
Q

What occurs after transcription?

A

> pre-mRNA dissociates from the template strand

> two DNA strands will re-form the double helix as it was originally

42
Q

What

A

introns present in the pre-mRNA molecule, after the initial process of transcription, need to be removed by a process called RNA splicing

43
Q

wheres does RNA Splicing occur?

A

> occurs in the nucleus

44
Q

What is RNA splicing?

A

production of a mature mRNA molecule

45
Q

What occurs to the mature mRNA molecule?

A

translated into polypeptides/proteins by ribosomes in the cytoplasm

46
Q

What is thE FIRST step of translation?

A
  1. Initiation: The use of the start codon AUG.
47
Q

What is the SECOND step of translation?

A
  1. Chain elongation: the building of the amino acid sequence from the codons.
48
Q

What is the THIRD step of translation?

A
  1. Termination: The completion of the mRNA sequence with a stop codon: UAG, UAA or UGA
49
Q

What is the process of translation?

A

a polypeptide chain is built using a sequence of codons in a mature mRNA molecule.

50
Q

Where does translation take place?

A

The site of translation is the ribosome in the cytoplasm.

51
Q

How do the ribosomes read the mature mRNA strand?

A

read the mature mRNA strand in the 5’ to 3’ direction starting at the start codon (AUG)

52
Q

How does initiation occur?

A

Two tRNA molecules move to the ribosome sites

> bond with the mRNA strand as determined by their complementary codons and anticodons

53
Q

Hows does initiation begin?

A

ribosome facilitates the formation of a peptide bond between the two amino acids.

> The ribosome moves along the mRNA resulting in a growing polypeptide chain

54
Q

How does chain elongation begin?

A

tRNA molecules continue to bring amino acids to the ribosome until a stop codon is reached.

55
Q

How do ribosomes create many copies of polypeptide chains? (chain elongation)

A

Many ribosomes can move along the mRNA one after the other, leading to the synthesis of many copies of the polypeptide chain in a short period of time.

56
Q

When does the termination process begin?

A

mature mRNA will continue making copies of the polypeptide chain until the miRNA message is sent and binds to mature mRNA.

57
Q

What is termination in the process of translation?

A

deactivates the mature mRNA,

> by promoting its destruction

> blocking its translation of it, preventing the expression of this gene

58
Q

What occurs after the peptide chain is complete?

A

When a stop codon is reached, the polypeptide chain is complete and it is released from the ribosome into the RER.

59
Q

Whats are genes and their main parts?

A

A gene is a sequence of DNA which is transcribed into RNA and contains three main parts.
Promotor,
Coding sequence
Terminator

60
Q

What is the promoter region of a gene?

A

The promoter functions as a binding site for RNA polymerase.

> responsible for the initiation of transcription
located immediately upstream of the gene’s coding sequence

61
Q

What is a gene coding sequence?

A

> The region of DNA that is transcribed by RNA polymerase is called the coding sequence

Context: After RNA polymerase has bound to the promoter, it causes the DNA strands to unwind and separate

62
Q

What is a proteome?

A

is the complete set of proteins expressed by an organism.

> assortment of proteins produced at a specific time in a particular cell or tissue type

63
Q

Difference between transcription and translation?

A

Transcription – Copying Gene’s DNA to make an RNA copy

Translation – Making (synthesising) a protein from RNA copy

BIOLOGY STAGE 2 RATGANG (4 decks)

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