Inheritance Paper 2 Flashcards
Definition of gene
Small section of DNA found in chromosomes
That codes for a specific sequence of amino acids to produce a specific protein
Definition of genome
Entire genetic material of an organism
3 Benefits of scientists understanding entire genome
1) we can search for genes linked to certain diseases e.g genes increasing the risk of developing cancer
2) helps to understand and treat inherited disorders e.g cystic fibrosis
3) we can trace human migration patterns from the past (helps people discover their ancestry)
DNA is a polymer made up of molecules called…
Nucleotides
Nucleotides (the molecules that make up the DNA polymer) consist of what 3 things
Base
Sugar
Phosphate group
In the nucleotides of DNA which can change out of the sugar, base and phosphate group
Bases
There are 4 different bases
(Phosphate and sugar group never change)
How many DIFFERENT nucleotides does DNA contain
4
As there are 4 different types of bases
DNA strands are….so the same bases always pair on the opposite strand (A always pairs with T and C always pairs with G)
Complementary
All facts about structure of DNA
DNA is a polymer made up of molecules called nucleotides which forms a double helix
A nucleotide consists of a phosphate group, sugar and base.
There are 4 different types of bases which is why there 4 different types of nucleotide
Strands of DNA are always complementary so A always pairs with T on the opposite strand and C always pairs with G on the opposite strand
What type of structure is a nucleotide
Molecule
What type of structure is a nucleotide
Molecule
What structures in a cell is DNA contained in
Chromosomes
Proteins are polymers of..,
Amino acids
What determines the shape of a protein
The specific order of amino acids
The specific order of amino acids determines the…of the protein
Shape
What determines the function of the protein
The shape of the protein
(Which is determined by the specific order of amino acids)
The shape of the protein determines what about the protein
Its function
What determines the specific order of amino acids in a protein (which then determines the shape and function of the protein)
Base sequence of a gene
(3 bases code for one amino acid)
How many bases code for one amino acid
3
A sequence of …. bases code for a particular…
3
Amino acid
The first stage of protein synthesis occurs in the…. and is called
Nucleus
Transcription
Name for first stage of protein synthesis
Transcription
Where does the first stage of protein synthesis occur (transcription)
Nucleus
What happens in transcription (first stage of protein synthesis)
1) base sequence of gene is copied into complementary template molecule (mRNA)
2) mRNA passes out of the nucleus and into the cytoplasm
Name for complementary template molecule in transcription (first stage of protein synthesis)
mRNA
Where does the mRNA (complementary template molecule) go once it’s left the nucleus
Cytoplasm
How many strands is mRNA
1 strand (it’s a single stranded molecule)
How are amino acids brought to the ribosome during translation (2nd part of protein synthesis)
By carrier molecules (tRNA)
Carrier molecules bring what to the ribosome during translation
Amino acids
Whole process of translation (2nd stage of protein synthesis)
1) mRNA molecule attaches to a ribosome
2) carrier molecules (tRNA) bring amino acids to the ribosome
3) ribosome reads triplets of bases on mRNA then joins the correct amino acids together in the correct order
4) when the protein chain is complete it folds up to form a specific shape which gives it a specific function
Where does translation occur (2nd part of protein synthesis)
Cytoplasm
Where does translation occur (2nd part of protein synthesis)
Cytoplasm
Whole process of protein synthesis (including both transcription and translation)
1) in nucleus, base sequence of gene is copied onto mRNA (complementary template molecule)
2) mRNA moves out of nucleus to cytoplasm
3) mRNA molecule attaches to a ribosome
4) carrier molecules (tRNA) bring amino acids to ribosome
5) ribosome reads triplets of bases on mRNA then joins the correct amino acids together in the correct order
6) once the protein chain is complete it folds up into a specific shape to give it a specific function
What happens in protein synthesis once the carrier molecules (tRNA) have brought the amino acids to the ribosome
Ribosome reads the triplets of bases on the mRNA to join together correct amino acids in correct order to form protein chain
In the first stage of protein synthesis the base sequence of the…is copied onto the…
Gene
mRNA
Mutation meaning
Change to a base
Name for change to a base in DNA
Mutation
True or false, most mutations (change in base to DNA) effect the shape and therefore function of a protein
False
Most mutations do not change the protein’s shape as the same amino acid is still coded for so the order of amino acids stays the same so the shape of the protein doesn’t change so its function doesn’t change
2 ways mutations may alter function of protein (although most of the time it has no effect as the same amino acid is coded for so the proteins shape stays the same so its function stays the same)
For enzymes it’s active site may change shape so it can no longer bind to the substrate
For structural proteins it may lose strength
1 way mutations can alter the function of proteins is that structural proteins lose..
Strength
1 way mutations can alter the function of proteins is that…proteins lose strength
Structural
1 way mutations can alter the function of proteins is that the…..of the enzyme changes shape so it can no longer bind to the…
Active site
Substrate
True or false, all parts of DNA code for proteins
False
There are also non- coding parts of DNA which don’t code for proteins
Non coding parts of DNA do what to genes
Switch them on and off
Mutations in non coding parts of DNA affect what
How genes are switched on and off
Mutations in ….. affect how genes are switched on and off
Non coding parts of DNA
(As non coding parts of DNA switch genes on and off)
In body cells all chromosomes come in pairs, one chromosome in each pair is from the…. and one chromosome in each pair is from the…
Mother
Father
Definition of alleles
Versions of a gene
How many copies of every gene do we have and why
2
One from our mother, one from our father
Why do we have 2 copies of every gene
One from our mother
One from our father
Genotype definition
Combination of alleles a person has
E.g Bb
Homozygous definition
When an individual has 2 copies of the same allele for a trait e.g BB
Homozygous definition
When an individual has 2 copies of the same allele for a trait e.g BB
Phenotype definition
Physical characteristic caused by genotype e.g blue eyes is the phenotype caused by bb
Heterozygous definition
Individual has 2 different alleles for a trait e.g Bb
Heterozygous definition
Individual has 2 different alleles for a trait e.g Bb
Dominant allele definition
Only one copy of the allele needed for the physical characteristic to be expressed
How many genes are most characteristics controlled by
Lots of genes acting together
(Very rarely its just one gene on its own)
True or false, each characteristic is normally only controlled by one gene
False
Each characteristic is controlled by lots of genes acting together
Very rarely a characteristic is controlled by only one gene
2 key inherited disorders I need to know about
Cystic fibrosis
Polydactyly
Cystic fibrosis is an inherited disorder to do with…
Cell membranes
How many genes is cystic fibrosis controlled by
One (a single gene)
Is cystic fibrosis dominant or recsseive
Recessive (you must have 2 copies of the alleles for the defective cell membrane to have the disorder)
All facts about cystic fibrosis
Inherited disorder
Disorder of the cell membranes
Caused by recessive allele
Polydactyly is an inherited disorder where you have extra..l
Fingers or toes
Is Polydactyly caused by a dominant or recessive allele
Dominant
Facts about Polydactyly
Inherited disorder caused by dominant allele where you have extra fingers or toes
What is embryo screening
Embryos tested to see if they have the alleles for inherited disorders
Issues with embryonic screening (where embryos are tested to see if they have the alleles for inherited disorders)
Expensive
Many embryos are destroyed (unethical)
What is gene therapy
Where scientist correct faulty alleles to treat inherited disorders
Gene therapy is where scientists correct….to treat…
Faulty genes
Inherited disorders
Advantages and disadvantages of sexual reproduction
Genetic variation
If environment changes, offspring may have survival advantage by natural selection
Slower than asexual reproduction
Requires more time and energy than asexual reproduction in order to find a mate
2 advantages of sexual reproduction
Genetic variation
If the environment changes, the offspring may have a survival advantage by natural selection
One advantage of sexual reproduction is that if the environment changes…
the offspring may have a survival advantage by natural selection
2 disadvantages of sexual reproduction
Slower than asexual reproduction
Requires more time and energy than asexual reproduction in order to find a mate
4 Advantages of asexual reproduction
Only one parent needed
More time and energy efficient than sexual reproduction as don’t need to find a mate
Faster than sexual reproduction
Many genetically identical offspring produced very quickly when conditions are favourable
One advantage of asexual reproduction is that Many genetically identical offspring are produced quickly when conditions are…
Favourable
2 Disadvantages of asexual reproduction
All offspring are identical so all offspring could die if conditions are unfavourable
Harmful mutations in parent would be passed down to all offspring
One disadvantage of asexual reproduction is that harmful… in one parent would be passed down to all offspring
Mutations
