inheritance Flashcards
what is an allele
different forms of the same gene
dominant
allele of a gene that is always expressed in the heterozygous genotype
recessive
allele that is not expressed in the phenotype when a dominant allele of the gene is present
genotype
alleles an organism has for a certain characteristic eg:BB, homozygous dominant
phenotype
how a gene is expressed. the ‘appearance’ of an organism resulting from its genotype
homozygous
genotype with the same alleles of a gene, eg: AA or aa
heterozygous
genotype with different alleles of a gene, eg:Aa
codominant
if 2 alleles are expressed in the same phenotype- they are called codominant
polygenic inheritance
when many characteristics are controlled by 2 or more genes working together’
what is an example of polygenic inheritance
human skin colour
why do the offspring from sexual reproduction vary genetically
huge variation in gametes, so it is random in which fertilisation takes place (RANDOM FERTILISATION)
list three ways how twins are identical caused by genetics
-eye colour
-DNA
-height
list three ways how twins are identical caused by environment
-personality
-weight
-hair colour
what is the shape of DNA
double helix shape
-made of subunits and nucleotides
what is the strand of a DNA molecule that codes for the making of proteins in a cell
the template strand
how many bases code for 1 amino acid and what is it called
-3
-triplet code
protein is made in the cytoplasm-in the ribosomes, DNA holds the genetic code for the protein in the nucleus but cannot leave the nucleus-how is this solved
genetic code is copies and transferred out the nucleus by RNA
what base does RNA contain instead of thymine
uracil
what sugar does RNA contain instead of deoxyribose
ribose
is an RNA molecule bigger or smaller than DNA
smaller
what are the three forms of RNA
-messenger mRNA
-transfer tRNA
-ribosomal rRNA
where does transcription take place
nucleus
where does RNA polymerase bind to
a region of non coding DNA in front of a gene
what happens to the DNA when RNA polymerase moves along one of the strands of DNA
the DNA strands unzip
what does mRNA use as a template so it can be made
the coding DNA in the gene
base pairing between the DNA & RNA ensures what
MRNA is complementary to the gene
what happens when the mRNA is made
the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
where does transcrpition take place
nucleus
what process happens when the mRNA is bound to the ribosome
translation
what does the transfer RNA bring to the ribosome
amino acids
I terms of the tRNA structure, what is the anticodon
-complementary to the codon of the amino acid
-pairing of codon and anticodon makes sure amino acids are brought to the ribosome in the correct order
what happens when the amino acids are joined together
a protein is made
-protein is a specific shape which determines the function
what is a nucleotide made of
-nitrogenous base
-sugar molecule
-phosphate group
what are the main points of natural selection
-variation of species
-due to random mutation
-survival
-reproduce
-pass on favourable allele
who came up with theory of natural selection
Charles Darwin
who discovered the first antibiotic and what was it
Alexander flemming- penicillin
how does a bacterium become resistant to penicillin
random mutation
how to bacteria reproduce passing on the allele (resistance)
asexually
what is a mutagen
increases the likelihood of a mutation happening
what is are two examples of a mutagen
-cigarettes
-ionising radiation
