Topic M - Inheritence Flashcards
Definition of a genome
The entire DNA of an organisms
Definition of gene
A section of a molecule of DNA that codes for a specific protein
PAPER 2
Describe the structure of a DNA molecule
2 strands coiled to form a double helix
PAPER 2
What are the strands in a DNA molecule linked by
A series of paired bases
- Adenine with Thymine ( A+T)
- Cytosine with Guanine ( C + G)
PAPER 2
What is special about an RNA molecule
It is single stranded and contains Uracil ( U ) instead of Thymine ( T)
PAPER 2
What are the 2 stages of protein synthesis
Transcription and Translation
PAPER 2
What is transcription
the enzyme RNA polymerase is involved in joining together the base sequence to make mRNA
PAPER 2
Describe the process of Transcription
- RNA polymerase binds to a region of non- coding DNA in front of a gene
- 2 DNA stands unzip + the RNA polymerase moves along one of the strands of the DNA
- RNA polymerase using the coding DNA in gene as a template to make mRNA = base paring
- Base paring between DNA + RNA polymerase= mRNA is complementary to the gene
- Once made, the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
PAPER 2
What is Translation
Assembling of protein
PAPER 2
Describe the process of Translation
- Amino acids brought to ribosome by transfer RNA (tRNA)
- Order in which amino acids are brought to the ribosome matches the order of the codons in mRNA
- Part of tRNA’s structure= anticodon=complementary to codon for amino acid
- Paring of codon + anticodon = amino acids brought to ribosome in the correct order
- Amino acids are joined together by ribosome = makes protein
Definition of restriction enzyme
Used to cut DNA at specific sites
Definition of ligase enzymes
Used to join pieces of DNA together
How are plasmids and viruses vectors ( things that move something )
transfer DNA into a cell
They take up pieces of DNA then insert this recombinant DNA into other cells
(Plasmid = transferred between bacteria Virus= insert DNA in organism they infect )
Definition of recombinant DNA
2 different bits of DNA stuck together
How can large amounts of insulin be manufactured
Manufacuted from genetically modified bacteria that are grown in a fermenter
what does a division of a cell by mitosis produce
2 cells that contain identical sets of chromosomes
what does mitosis occur during
growth
repair
cloning
asexual reproduction
explain the stages of mitosis
- cells that are not dividing contain long strings of DNA
- before cell divides, cell duplicates DNA and forms X- shaped chromosomes
- chromosomes line up at centre of cell
- cell fibres pull the arms of each chromosome to opposite ends of the cell
- membranes form round each of the sets of chromosomes= nuclei of 2 new cells
- cytoplasm divides= 2 new genetically identical cells
what does a division of a cell by meiosis produce
4 cells, each with half the number of chromosomes
= formation of genetically different haploid gametes
explain the stages of meiosis
- before cell divides, cell duplicates DNA and forms X- shaped chromosomes
- 1st division= chromosomes line up in their pairs arcos the centre of cell ( 1 chromosome from mother + one from father )
- pairs are pulled apart = each new cell only has 1 copy of each chromosome
- pulling apart = mixing up mother and fathers chromosomes into new cells = genetic variation
- 2nd division = chromosomes line up across centre (again )
- arms of chromosomes = pulled apart
- = 4 haploid gametes each containing half the original no. of chromosome = genetically different
in human cells what is the diploid number of chromosomes
46
in human cells what is the haploid number of chromosomes
23
what does random fertilisation produce
genetic variation of offspring
what can variation within species be
genetic
environmental
combination of both
PAPER 2
how does a change in DNA effect the phenotype
alters the sequence of amino acids in a protein
PAPER 2
what effect do most genetic mutations have on the phenotype
no effect (some have a small effect but rarely do they have a significance)
PAPER 2
what can the incidence of mutations be increased by
exposure to ionising radiation (gamma + x-rays) chemical mutagens ( chemicals in tobacco)
explain Darwin’s theory of evolution by natural selection
Penguins Only Carry Socks Round Corners Every Afternoon
- Variation in population
- organism produce more offspring than can survive
- therefore = competition for resources
- best adapted to environment= most likely to survive 5. survive= reproduce
- reproduce= characteristics passed on to offspring
- over many generations= increase in successful characteristics
- other characteristics die + no reproduce
- evolution= shift in proportion of that characteristics= allelic frequency ( different forms of same gene)
- evolution= only happen to species not individual
- therefore evolution= long ( thousand years/generations)
- DNA is what gets passed down- expressed info as characteristics
resistance to antibiotics can increase in what kind of conditions
bacterial populations
what can an increase in resistance to antibiotics cause
infections being difficult to control
what alternative forms do genes exist in
alleles
what do alleles do
???give rise to differences in inherited characteristics
definition of allele
determine our inherited characteristics
definition of dominant
??? where only dominant allele is expressed- overpowers recessive
definition of recessive
an allele who’s features eg. blue eyes is only seen when there are 2 copies ( homozygous)
definition of homozygous
an organism whose alleles for a particular gene are both the same
definition of heterozygous
an organism with a pair of genes where each is a different allele ( ie. 1 dominant, 1 recessive )
definition of phenotype
the visible ( as opposed to genetic) characteristics of an organism
definition of genotype
a name for the full set of genes possessed by an organism
a version of a gene- each version codes for a different phenotype
definition of co-dominance
both alleles ( characteristics ) are expressed ( 2 different capital letters)
what are most phenotypic features the result of
polygenic inheritance rather than single genes
explain the process of the production of human insulin from genetically modified bacteria
- DNA = extracted from human cells
- Restriction enzymes cut out at specific on the DNA to cut out the insulin gene
- Plasmid DNA = extracted from bacteria cells
- Same restriction enzymes = cut plasmid DNA
- Ligase enzymes stick the human insulin gene into the bacteria plasmid - plasmid = vector
- Recombinant plasmid = put into bacteria = transgenic
- bacteria ( grown in fermenter ) + reproduce rapidly = make large quantities of human insulin
