4.1: DNA, genes & chromosomes Flashcards by Shaun Joseph

What is a gene

Sequences of bases in DNA that codes for a specific polypeptide or a functional RNA

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what is the sequence of bases in DNA that codes for a specific polypeptide or a functional RNA

a gene

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What is the locus

position of a gene in DNA

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what is the name for the position of a gene in DNA

locus

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what does the sequence of bases in DNA determine

the sequence of amino acids in a polypeptide

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what does the sequence of amino acids in a polypeptide determine

shape and function of a protein

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what does the shape and function of a protein determine

characteristics of a cell

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What is an allele

The various forms of a gene

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Is prokaryotic DNA continuous or does it have a start/end?

continuous

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Is eukaryotic DNA continuous or does it have a start/end?

has a start/end

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what is the name for the various forms of a gene

an allele

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What are homologous chromosomes

2 chromosomes with the same genes in the same loci

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what are 2 chromosomes with the same genes in the same loci called

homologous chromosomes

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what is a diploid

2 sets of chromosomes

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what is the name for 2 sets of chromosomes

a diploid

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what is the name for the number and type of chromosomes in a cell

karyotype

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what is the karyotype

the number and type of chromosomes in a cell

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can you have haploid homologous chromosomes?

no, only diploid

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what is a bivalent

a replicated homologous pair of chromosomes

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what is the name given to a replicated homologous pair of chromosomes

a bivalent

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What is the genetic code

sequence of nucleotides that code for a specific polypeptide

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what is the sequence of nucleotides that code for a specific polypeptide

the genetic code

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how many bases are there in DNA

How many different amino acids are there in proteins

What are exons in the genetic code

coding regions

what are the coding regions in the genetic code

exons

what are introns in the genetic code

non-coding regions

what are the non-coding regions in the genetic code

introns

What is the role of a STOP codon and how does it do this

does not code for an amino acid and therefore stops the production of a protein

What is meant by 'degenerate code' in relation to the genetic code

each triplet codes for a specific amino acid and each amino acid may have more than one code

what is meant by 'non-overlapping' in relation to the genetic code

each base is only read once

what is meant by 'universal code' in relation to the genetic code

each triplet codes for the same amino acid in ALL organisms

what is a genome

complete set of genes in a cell/organism

what is a proteome

full set of proteins that can be made by the genome

what is it called when there is a series of 3 consecutive bases in the DNA

triplet

what is it called when there is a series of 3 consecutive bases in the mRNA

codon

what is it called when there is a series of 3 consecutive bases in the tRNA

anticodon

how many genes does mRNA code for

only one

how many strands is mRNA

single stranded

What is the relation between mRNA and DNA

As mRNA is transcribed from DNA, its codons are complementary to DNA's triplets

what does the sequence of codons on the mRNA determine

the sequence of amino acids brought to the ribosome by tRNA

describe the structure of mRNA

relatively long helical polynucleotide

describe the structure of tRNA

single stranded folded into a 'clover leaf' shape and relatively small. Has an amino acid attachment site (top), and has an anticodon (bottom)

what does the anticodon on a tRNA molecule determine

determines which tRNA attaches to which mRNA

how many chromosomes are in a gamete

23 (haploid)

how many chromosomes are in a somatic cell

46 (diploid)

state how the quantity of chromosomes in a gamete differs from that in a somatic cell

half in a gamete (haploid)

What do 2 haploid gametes produce when they fertilise

a diploid cell

explain the advantage of DNA being a chemically stable molecule

has to remain the same from generation to generation

explain the advantage of mRNA being broken down relatively quickly

to be reused and avoid wasteful production of proteins

what is the main way that eukaryotic DNA differs from prokaryotic DNA in relation to proteins

Eukaryotic DNA is wrapped around histones whereas prokaryotic DNA is not associated with proteins

out of eukaryote, prokaryote and mitochondrial DNA, which of these possesses introns

only eukaryotic DNA

Name an organelle other than eukaryotic DNA, prokaryotic DNA and mitochondrial DNA, that has its own DNA

chloroplast

Describe 3 ways in which an ATP molecule differs from a nucleotide in a DNA molecule

1 - ATP has 3 phosphate groups, DNA nucleotide has 1 phosphate group 2 - ATP has ribose sugar group, DNA nucleotide has deoxyribose sugar group 3 - ATP can only have adenine base, DNA nucleotide can have 4 different nitrogenous bases (A,T,G,C)

Describe the difference in structure of a deoxyribose sugar (DNA nucleotide) and a ribose sugar (ATP)

ribose = hydroxyl group below carbon 2 (normal) whereas deoxyribose has hydrogen atom below carbon 2