Biology - Topic 3 - Genetics Flashcards
Which structures are found inside the nucleus?
chromosomes
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 would happen to the number of chromosomes in a zygote if two body cells were used in fertilisation?
it would have twice the number it should
How many chromosomes does a human gamete
contain?
23
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?
double helix
What is a chromosome made out of?
DNA and proteins (to package the DNA)
What are the letters of the bases that form the DNA code?
A, C, T and G
How do the 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
How is the active site of an enzyme formed?
by folding of protein/polypeptide/amino acid chains
What molecule is produced in transcription?
mRNA or messenger RNA
What base does mRNA contain that DNA does not?
uracil
What is the name of the enzyme that allows
transcription to occur?
RNA polymerase
The mRNA nucleotides fit together with the nucleotides on the DNA template strand. What word describes bases that fit together?
complementary
Where does transcription occur in a cell?
nucleus
Where does translation occur in a cell?
cytoplasm
What has to bind to an mRNA molecule for translation to occur?
ribosome
What does translation produce?
a polypeptide / protein
What molecule carries amino acids to the mRNA in the ribosome?
tRNA
What has to happen to the polypeptide for an enzyme in order for it to become a functional enzyme?
It has to fold.
How many bases does a codon contain?
three
What does each codon contain the code for?
the addition of a particular amino acid to the polypeptide chain
What is the name of the process in which the genetic code is used to make a polypeptide?
translation
A change in the bases of a gene creates a genetic variant. What is this sort of change called?
mutation
Why might a mutation in a codon not cause a change in the polypeptide produced?
It does not affect the amino acid that is coded for.
Why can a difference of a single amino acid change how a protein functions?
It can interfere with the way the polypeptide chain(s) fold(s).
Why might a mutation in the non-coding region before a gene cause an increase in the production of a certain protein?
The mutation causes RNA polymerase to bind better.
What is an organism’s phenotype?
its observable 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 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 monohybrid inheritance?
inheritance of alleles of one gene
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?
50% or 0.5
What letters are used to describe the different human blood groups?
A, B, O
Name the four bases in DNA.
adenine, thymine, cytosine, guanine
Why can DNA be matched to the person it came from?
Everybody has a slightly different orders of bases in their DNA.
Is human eye colour coded for by one gene or many genes?
many
One gene codes for the cell membrane protein CFTR. There are many alleles for the CFTR gene. How many alleles do you have for the CFTR gene in one of your body cells?
two
A mutation of the CFTR gene can lead to the disorder cystic fibrosis. What is a mutation?
a change in the order of bases that form the gene
Cystic fibrosis is an inherited disorder. What does that mean?
It is passed from parent to offspring in the genes in a gamete.
What research, finished in 2003, was the first effort to map a complete human genome?
Human Genome Project
How could a map of a person’s genome help identify diseases they might develop?
Some alleles show an increased risk for the person of developing a genetic disorder.
How could a map of a person’s genome identify which medicines they should be given?
Some alleles affect how well medicines work in the body, including problems they can cause.
