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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

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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
How are ribosomes involved in translation?
Ribosomes move along the mRNA strand ranslating the mRNA code into a sequence of amino acids, called a polypeptide molecule
26
What is MiRNA
Micro RNA are small non-coding RNA molecules consisting of approximately 22 nucleotides. > regulating gene expression after transcription has occurred.
27
What is the function of miRNA?
They exert gene regulation by binding to a small section of a specific messenger RNA (mRNA) molecule, preventing it from being translated.
28
What are amino acids?
are the building blocks of polypeptides and protein molecules.
29
What are polypeptides?
A polypeptide is a sequence of amino acids linked together by strong peptide bonds
30
What two DNA strands does DNA consist of?
>The coding (non-template) strand >The template strand
31
What is the non-template coding strand?
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
What is the template strand?
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
What does the coding strand consist of?
triplets of bases called DNA codons.
34
What does the template strand consist of?
As the template strand is complementary to the coding strand it consists of triplets of bases called DNA anticodons.
35
What happens to mRNA during transcription?
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
What occurs to the mRNA codons in transcription?
tRNA molecules with complementary anticodons to the mRNA codons bring specific amino acids to the growing polypeptide chain.
37
What are codons?
Triplets of bases are the smallest units necessary to code for all 20 amino acids. Example GCG UGG UGU
38
How does mRNA translate codons into amino acids?
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
What is transcription?
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
What is the process of transcription?
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
What occurs after transcription?
> pre-mRNA dissociates from the template strand > two DNA strands will re-form the double helix as it was originally
42
What
introns present in the pre-mRNA molecule, after the initial process of transcription, need to be removed by a process called RNA splicing
43
wheres does RNA Splicing occur?
>occurs in the nucleus
44
What is RNA splicing?
production of a mature mRNA molecule
45
What occurs to the mature mRNA molecule?
translated into polypeptides/proteins by ribosomes in the cytoplasm
46
What is thE FIRST step of translation?
1. Initiation: The use of the start codon AUG.
47
What is the SECOND step of translation?
2. Chain elongation: the building of the amino acid sequence from the codons.
48
What is the THIRD step of translation?
3. Termination: The completion of the mRNA sequence with a stop codon: UAG, UAA or UGA
49
What is the process of translation?
a polypeptide chain is built using a sequence of codons in a mature mRNA molecule.
50
Where does translation take place?
The site of translation is the ribosome in the cytoplasm.
51
How do the ribosomes read the mature mRNA strand?
read the mature mRNA strand in the 5’ to 3’ direction starting at the start codon (AUG)
52
How does initiation occur?
Two tRNA molecules move to the ribosome sites > bond with the mRNA strand as determined by their complementary codons and anticodons
53
Hows does initiation begin?
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
How does chain elongation begin?
tRNA molecules continue to bring amino acids to the ribosome until a stop codon is reached.
55
How do ribosomes create many copies of polypeptide chains? (chain elongation)
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
When does the termination process begin?
mature mRNA will continue making copies of the polypeptide chain until the miRNA message is sent and binds to mature mRNA.
57
What is termination in the process of translation?
deactivates the mature mRNA, > by promoting its destruction > blocking its translation of it, preventing the expression of this gene
58
What occurs after the peptide chain is complete?
When a stop codon is reached, the polypeptide chain is complete and it is released from the ribosome into the RER.
59
Whats are genes and their main parts?
A gene is a sequence of DNA which is transcribed into RNA and contains three main parts. Promotor, Coding sequence Terminator
60
What is the promoter region of a gene?
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
What is a gene coding sequence?
>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
What is a proteome?
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
Difference between transcription and translation?
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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