4.2 DNA and Protein Synthesis Flashcards
1
Q
What is a genome?
A
The complete set of genetic information contained in the cells of an organism
2
Q
What is a proteome?
A
The complete set of proteins that can be produced by a cell
3
Q
Describe the structure of mRNA
A
- A long, single strand
- Its base sequence is complementary to the DNA it was transcribed from
4
Q
Suggest advantages of using mRNA rather than DNA for translation
A
- Shorter and contains uracil = breaks down quickly so no excess polypeptide forms
- Single stranded and linear = ribosome moves along strand and tRNA binds to exposed bases
- Contains no introns
5
Q
Describe the structure of tRNA
A
- Single strand of around 80 nucleotides that is folded over into a clover leaf shape
- On one end is an anti-codon, on the opposite end is an amino acid binding site
6
Q
What is produced by transcription?
A
mRNA
7
Q
Where does transcription take place?
A
In the nucleus
8
Q
Describe how mRNA is produced in the nucleus of a cell
A
- DNA helicase breaks the H bonds holding the complementary base pairs
- One DNA strand acts as a template
- Free RNA nucleotides are attracted to DNA template strand
- RNA nucleotides bind to their complementary base pair on the template strand
- RNA polymerase joins RNA nucleotides together
- Pre-mRNA is spliced to remove the introns
9
Q
Explain the role of tRNA in the process of translation
A
- mRNA attaches to a ribosome
- Anticodons on tRNA are complementary to specific codons on mRNA
- A specific amino acid is bound to tRNA
- This amino acid is carried to the ribosome
- Ribosome moves along mRNA
- Peptide bonds form between adjacent amino acids
- Requires ATP
- Ribosome detaches from mRNA when stop codon is reached
10
Q
Outline the process of transcription
A
- DNA uncoils into two strands with expose bases
- One is used as a template
- Free nucleotides line up next to their complementary bases and are joined together by RNA polymerase
10
Q
Describe how DNA is packed into a chromosome
A
- DNA molecule combines with histones
- DNA-histone complex begins to coil and fold to form loops
- Loops coil further and pack together to form the chromosome
11
Q
What happens to mRNA after transcription?
A
- In eukaryotic cells, pre-mRNA must be spliced to remove introns, leaving only the coding regions
- It them moves out of the nucleus and attaches to a ribosome
12
Q
What is produced by translation?
A
Proteins
13
Q
Where does translation take place?
A
In the cytoplasm
14
Q
Outline the process of translation
A
- Anticodon of tRNA attaches to the complementary bases on the mRNA
- Amino acids bound to tRNA form peptide bonds, continuing to form a polypeptide chain until a stop codon is reached
- This process requires ATP
