Topic 3 - Genetics Flashcards
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.
Triple only- What molecule is produced in transcription?
mRNA or messenger RNA
Triple only- What base does mRNA contain that DNA does not?
uracil
Triple only-What is the name of the enzyme that allows transcription to occur?
RNA polymerase
Triple only-The mRNA nucleotides fit together with the nucleotides on the DNA template strand. What word describes bases that fit together?
complementary
Triple only- Where does transcription occur in a cell?
nucleus
Triple only-Where does translation occur in a cell?
cytoplasm
Triple only-What has to bind to an mRNA molecule for translation to occur?
ribosome
Triple only-What molecule carries amino acids to the mRNA in the ribosome?
tRNA
Triple only- 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
Triple only-What does each codon contain the code for?
the addition of a particular amino acid to the polypeptide chain
Triple only-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
Triple only-What does translation produce?
a polypeptide
Triple only- 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.
Triple only- 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).
Triple only- What has to bind to an mRNA molecule for translation to occur?
ribosome
Triple only- 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 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.
Triple only- What is monohybrid inheritance?
inheritance of alleles of one gene
Triple only- In monohybrid inheritance, what is the theoretical probability of parents who are both heterozygous for a gene producing an offspring that is also heterozygous for the gene?
probability 50 per cent or half
Triple only- In monohybrid inheritance, what is the theoretical ratio of dominant to recessive phenotypes produced by parents who are both heterozygous for the characteristic?
03:01
Triple only- What letters are used to describe the different human blood groups?
A, B, O
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
Who devised the laws of inheritance and why wasn’t his methods accepted at the time?
Mendel
Published in a little-known journal
What is a type of mutation when bases swap positions?
Substitution.
What is the dominant eye colour?
Brown
How many base pairs in a human genome?
How many base pairs in DNA?
3 billion
4
What molecules are used to copy DNA in protein synthesis?
Enzymes
What occurs during transcription?
A mRNA copy of a section of a DNA strand is made.
Problems with selective breeding?
Reduced variation
What are the sex chromosomes pair and what are they for male and female?
The sex chromosomes are the 23rd pair.
XX = female
XY = male
What are alleles?
Forms of the same gene.
What is the phenotype of the genotype I^B I^O?
Phenotype B for the blood group.
What percentage of offspring have blue eyes from a cross between two homozygous dominant parents?
0% B is the dominant allele for brown eyes. bb will only get you blue eyes.
What percentage of offspring have blue eyes from a cross between two heterozygous parents?
25% B is the dominant allele for brown eyes. bb will only get you blue eyes.
What is the two types of variation?
Environmental
Genetic
What does variation mean?
A greater chance that some offspring will be better suited to new conditions and so will be more likely to survive and reproduce.
What does meiosis produce?
Gametes
4 haploid daughter cells which is how gametes are produced.
How to get DNA? DNA extraction?
- Peel the skin from half a kiwi fruit and mash it up.
- Mix a teaspoon of salt and small volume of washing up liquid into the fruit.
- Gently heat this mixture at about 60°C for five minutes.
- Filter the mixture and retain only the filtrate (the filtered liquid).
- Cool using an ice bath and gently pour chilled ethanol onto the top of the filtrate.
What are the benefits about the human genome project?
Can indicate their risk of developing diseases that are caused by different alleles of genes and what medicines can be used to treat the person effectively.
What is discontinuous variation?
Where the the data can only take a limited set of values. Bar chart, the bars don’t touch.
What is continuous variation?
Where the data can be any value in a range. Bar charts, the bars touch.
What is codominance?
When both alleles for a gene affect the phenotype, we say they are codominant.
The sequence of Meiosis?
The steps of Transcription?
- RNA polymerase attaches to a start codon in the DNA
- mRNA is transcripted base by base
- RNA is similar to a DNA complementary strand, except A bonds to U(uracil) and RNA is single stranded
- mRNA strand escapes the nucleus through tiny pores
The steps of Translation?
- mRNA escapes out tiny pores in the nucleus to the cytoplasm
- A ribosome attaches to the mRNA
- Complementary tRNA with an anticodon and a specific amino acid attaches to an mRNA codon
- Ribosomes causes peptide bonds to form between amino acids.tRNA is released
- At the stop codon, ribosomes are released
- The protein chain is released and folds to form a polypeptide(protein)
