reproduction and inheritance Flashcards
what type of cells are human cells
diploid
what does diploid mean
2 comes of each chromosome arranged in pairs
how many chromosomes does a human cell have
46
where are chromosomes found
nucleus of the cell
what are chromosomes
long lengths of DNA coiled up
what is a gene
a short section of DNA
what is each separate gene
a chemical instruction that codes for a particular protein
what are different versions of the same gene called
alleles
what I the structure of DNA
double helix
four different bases
adenine
cytosine
guanine
thymine
what compliments A
T
what compliments C
G
what are the two strands of DNA held together by
bases
what are proteins made up of
chains of amino acids
how does each protein have a different function
the chains fold up to give each protein a different, specific shape, therefore the enzymes have different active sites
what is a codon
each amino acid is coded by a sequence of 3 bases in the gene
how Manu possible codons are there
64
how many amino acids are there
20
what stages are proteins made in
transcription
translation
where are proteins made
ribosomes
why can’t DNA move to the ribosome
it is found in the nucleus and is too big to move out
what is used to get info from the DNA to the ribosomes
messenger RNA (mRNA)
what is different about the bases in mRNA than in DNA
uses uracil (U) instead of thymine (T)
what enzyme joins together the base sequence to make mRNA
RNA polymerase
4 stages of transcription
- RNA polymerase binds to a region of non-coding DNA in front of a gene
- the 2 DNA strands unzip and the RNA polymerase moves along one of the strands in the DNA
- It uses the coding DNA in the gene as a template to make the mRNA. Base pairing between the DNA and RNA ensures that mRNA is complimentary to the gene
- Once made, the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
what is it called when the protein is assembled in protein synthesis
translation
4 stages of translation
- amino acids are brought to the ribosome by another RNA molecule called tRNA
- the order in which the amino acids are brought to the ribosome matches the order of the codons in mRNA
- part of the tRNA’s structure is called an anticodon as it is complimentary to the codon for the amino acid. the pairing of the codon and anticodon makes sure that the amino acids are brought to the ribosome in the correct order
- the amino acids are joined together by the ribosome making a protein
what type of reproduction involves mitosis
asexual reproduction
what is asexual reproduction
asexual reproduction involves only one parent. the offspring have identical genes to the parent so there is no variation between parent and offspring
what is mitosis
when a cell reproduces itself by splitting to form 2 cells with identical sets of chromosomes
what organisms reproduce asexually
bacteria and plants
process of mitosis
- the DNA duplicates, forming X-shaped chromosomes, each arm a duplicate of the other
- the chromosomes line up at the centre of the cell and cell fibres pull them apart, each arm of the chromosomes go to opposite ends
- membranes form around each of the sets of chromosomes becoming nuclei of each cell
- cytoplasm divides leaving 2 identical cells
what type of reproduction involves meiosis
sexual reproduction
what is sexual reproduction
the fusion of male and female gametes. Because there are 2 parents, the offspring contain a mixture of their parent’s genes
what is meiosis
meiosis produces 4 hapolosid cells whose chromosomes are not identical
process of division 1 meiosis
- DNA duplicates and forms x-shaped chromosomes, each arm is an exact copy of the other
- chromosomes line up I pairs in the centre of the cell, one chromosome in each pair is from the mother and one from the father
- pairs are pulled apart, so each cell has only one copy of each chromosome
- each new cell has a mixture of the mother’s and father’s