Inheritance Flashcards
Define the terms gene, locus and allele.
Gene — length of DNA / sequence of DNA nucleotides coding for a protein / polypeptide
Locus — the position of a gene / allele on a chromosome
Allele — alternative / different form of a gene
Describe how you would carry out a test and use it to determine the genotype of an, e.g. “red-eyed fruit fly”.
Cross with white-eyed fly (recessive) / CWCW;
If all red-eyed, then CRCR;
If some apricot eyed- then CRCA;
If some honey-eyed then CRCW;
If some white-eyed then CRCW
Name the type of gene represented by lacY
Structural gene
Name the protein product coded for by lacY and state the precise role of this protein.
Lactose permease;
Movement / transport of lactose into cell; OR makes cell surface membrane more permeable to lactose;
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Describe and suggest explanations for the population growth curve shown in Fig 7.3
Population increases, then levels off, increases, then levels off;
(First increase) glucose metabolised / respiration;
(First levelling off) glucose has run out; lactose hydrolysed / broken down into glucose / galactose;
(Second increase) glucose / galactose metabolised / respired;
(Second levelling off) lactose / galactose / glucose has run out
Suggest a reason for the tight junctions between chemoreceptor cells.
No movement of chemicals / substances / ions, between the chemoreceptor / cells
Describe how the contact of cell A with Na+ can result in an action potential in sensory neurone B.
Na+ ions enter chemoreceptor cell through microvilli / channel proteins;
Cell surface membrane depolarised;
Receptor potential;
Ref to threshold;
Voltage gated calcium ion channels open;
Ca2+ ions enter cytoplasm;
Vesicles of neurotransmitter binds to receptor on postsynaptic membrane;
Sodium channels open OR Na+ enter sensory neurone;
Postsynaptic membrane / sensory neurone membrane depolarised
Explain how a mutation of the TYR gene can result in albinism.
Base substitution / deletion / insertion OR frame shift;
Change in primary / secondary / tertiary structure of protein / polypeptide;
Result may lead to amino acid coding for stop codon;
So no / inactive tyrosinase produced;
Tyrosine not converted to DOPA / dopaquinone;
Melanin not formed
Explain how the expression of the TYR gene leads to the production of melanin.
TYR gene codes for tyrosinase;
Converts tyrosine to DOPA;
Converts DOPA to dopaquinone
Dopaquinone converted to melanin
Explain how a gene mutation can lead to an enzyme not functioning properly or not being produced.
Base / nucleotide insertion / deletion / substitution;
Frameshift;
Changes primary structure / amino acid sequence;
Changes folding / 3D shape of enzyme / protein;
Active site does not bind / fit substrate/ complex molecules
State the term used to describe a protein that is involved in the control of gene expression in eukaryotes.
Transcription factor
