Topic Three Flashcards
Genetics
Which structures are found inside the nucleus?
chromsomes
Which substance forms a long strand in each chromosome?
DNA
How do body cells make copies of themselves?
cell division, mitosis
How many chromosomes are there in a human body cell nucleus?
46
What happens in fertilisation?
two gametes fuse
What is the name of the cell formed in fertilisation?
zygote, fertilised egg cell
Which term means producing more of the same kind of organism?
reproduction
What is the name of the human male gamete?
sperm cell
The DNA strand in a chromosome contains sections that carry instructions for characteristics. What are these sections called?
genes
What molecule forms the genome of an organism?
DNA
Where are genes found?
[in sections of DNA] on chromosomes
What does a gene carry the instructions for?
making a protein
A protein is made by linking together smaller molecules. What are these smaller molecules called?
amino acids
What is any molecule made of repeating units called?
a polymer
A human cell contains 46 strands of DNA. Is it diploid or haploid?
diploid
Are the cells produced by meiosis haploid or diploid?
haploid
Are the cells produced by mitosis haploid or diploid?
diploid
What shape is DNA?
a double helix
What is a chromosome made out of?
DNA and proteins [to package the DNA]
What shape is a DNA molecule?
double helix
What part of a DNA strand contains the instructions for a protein?
gene
What are the letters of the bases that form the DNA code?
A,C,T and G
How do these bases pair up in DNA?
A with T, C with G
Apart from bases, what other parts are needed in a DNA molecule?
phosphate group, sugar
What is one phosphate group, one sugar and one base called?
nucleotide
Why is DNA a polymer?
It is made of many nucleotides joined in a chain.
Give an example of a protein.
any example. E.g. an enzyme
How is the active site of an enzyme formed?
by folding of protein/polypeptide/amino acid chains
Why are proteins polymers?
They are made of many amino acids joined in a chain.
How many bases does a codon contain?
three
A change in the bases of a gene creates a genetic variant. What is this sort of change called?
mutation
What is an organism’s phenotype?
its observed characteristics
What are different versions of the same gene called?
alleles
What sort of variation do alleles cause in organisms?
genetic variation
When we consider one gene, what word is used to say that both alleles are the same?
homozygous
If a dominant allele has the letter A, how would you show that an organism is heterozygous?
Aa
What word describes the characteristics caused by the alleles of a gene?
phenotype
What word describes the alleles of a gene found in an organism?
genotype
What word describes an allele that only has an effect if an organism has two copies?
recessive
A genotype is written QQ. What does this tell you?
It is homozygous for the dominant allele.
What is a probability?
the chance of an event occurring
If the occurrence of an event has a probability of 1, what does this mean?
It is certain to occur.
How can we show the possible inheritance of alleles by offspring from their parents?
genetic diagram, Punnett square
Which type of diagram is used to show the inheritance of a characteristic through different generations in a family?
family pedigree
If the genotype for one gene of a rabbit is Bb, where B is the allele for brown coat and b the allele for black coat, what is the rabbit’s phenotype?
brown
What are the possible allele combinations of offspring from heterozygous parents who are both Aa for a gene?
AA, Aa and aa
A human egg cell that contains an X sex chromosome is fertilised by a sperm cell containing a Y sex chromosome. What will be the sex of the baby that develops?
male
What is the theoretical probability of a couple having a baby boy?
probability 50 per cent or half
