3.4 Genetic information, variation and relationships between organisms: Flashcards
3.4.1 DNA, genes and chromosomes
Name the fixed position occupied by a gene on a DNA molecule. (1)
Locus / loci
3.4.1 DNA, genes and chromosomes
Describe how a gene is a code for the production of a polypeptide. Do not include information about transcription or transalation in your answer. (3)
Base / nucleotide sequence (1)
In triplets (1)
Determines order of amino acid sequence (1)
3.4.1 DNA, genes and chromosomes
Define the term exon. (1)
Base / nucleotide coding for a polypeptide.
3.4.1 DNA, genes and chromosomes
Describe how a phosphodiester bond is formed between 2 nucleotides within a DNA molecule. (2)
Condensation reaction (1)
between phosphate and deoxyribose (1)
catalysed by DNA polymerase (1)
3.4.1 DNA, genes and chromosomes
Name the protein associated with DNA in a chromosome. (1)
Histones.
3.4.1 DNA, genes and chromosomes
Show three differences between a prokaryotic cell and plant cell. (1)
PLANT CELL:
Linear, double stranded, long.
PROKARYOTIC CELL:
Circular, single-stranded, short.
3.4.1 DNA, genes and chromosomes
Define ‘non-coding base sequences’ and describe where the non-coding multiple repeats are positioned in the genome (2).
DEFINITION:
does not code for proteins / polypeptides.
WHERE:
positioned between genes.
3.4.1 DNA, genes and chromosomes
The nucleus and a chloroplast of a plant cell both contain DNA. Give three ways in which the DNA in a chloroplast is different from DNA in the nucleus. (3)
- DNA in chloroplast is circular whereas DNA in nucleus is linear.
- DNA in the chloroplast is shorter whereas DNA in the nucleus is longer.
- DNA in chloroplast is not associated with histones whereas DNA in nucleus is associated with histones.
3.4.1 DNA, genes and chromosomes
Some DNA nucleotides have the organic base thymine, but RNA nucleotides do not have thymine. RNA nucleotides have uracil instead of thymine. Give one other difference between the structure of a DNA nucleotide and
the structure of an RNA nucleotide. (1)
> Deoxyribose pentose sugar in DNA and ribose pentose sugar in RNA.
3.4.1 DNA, genes and chromosomes
Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide. Give two reasons why.
- Triplets code for the same amino acid as DNA is degenerate.
- Occurs in introns / non-coding sequences.
3.4.1 DNA, genes and chromosomes
Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells. (5)
COMPARE:
1. Nucleotides joined by phosphodiester bonds.
2. Nucleotide structure is the same.
CONTRAST:
1. EC DNA is longer whereas PC DNA is shorter.
2. EC DNA is linear whereas PC DNA is circular.
3. EC DNA is associated with proteins whereas PC DNA is not associated with proteins / histones.
3.4.1 DNA, genes and chromosomes
What is a homologous pair of chromosomes?
Two chromosome that carry the same gene.
3.4.1 DNA, genes and chromosomes
What does DNA molecule and its associated molecule form?
A chromosome.
3.4.1 DNA, genes and chromosomes
What is a gene?
A base sequence that codes for amino acid sequence for amino acid sequence and the functional RNA.
