Genetic info+Variation Flashcards
gene
section of DNA that codes for the sequence of amino acids in a polypeptide and functional RNA
eukaryotic DNA vs prokaryotic DNA
eukaryotic-long, linear, histones
prokaryotic (mitochondria+chloroplasts)-short, circular, no histones
what does a gene code for
amino acid sequence of polypeptide, a functional RNA
what is a locus
location of the gene on the strand of DNA
3 properties of genetic code
universal, non overlapping, degenerate
Introns vs Exons
Introns-non coding multiple repeats of bases ( removed via splicing before being read)
Exons-coding bases
histone
stabilising protein in chromosomes
centromere
protein that connects 2 chromatids
haploid vs diploid
haploid-eg sperm, egg has 23 chromosomes
diploid-eg normal cell has 23 chromosome pairs
what are nucleic acids
eg RNA, DNA
made up of pentose sugar, phosphate group, nitrogenous base
allele
code for slightly different versions of the same polypeptide
homologous pair
corresponding pairs of chromosomes that are the same size and posses the same genes and centromere position
tRNA structure key features
attachment point of amino acids
H bonds between base pairs
anti-codon loop
(clover shape)
the role of RNA
transcription and translation
DNA vs RNA
DNA:
double stranded helix, longer, deoxyribose, ATCG
RNA:
single stranded helix, shorter, ribose, AUCG
mRNA structure key features+ purpose
linear shape, proteins made in cytoplasm as DNA is too large to exit nucleus RNA transcribes it and carries info out via nuclear pores
RNA transcription steps
1-RNA polymerase attaches to the DNA-
H bonds break, uncoil+ expose bases,1 strand used as template
2-complementary mRNA formed-
free RNA nucleotides line up along exposed bases
3-RNA polymerase moves down DNA strand-
mRNA strand assembled, H bonds reform+ re coil once polymerase has passed
4-RNA polymerase reaches stop signal-
enzyme used in transcription
RNA polymerase
pre-mRNA vs mRNA
pre-mRNA=eukaryotes as they contain introns
mRNA=prokaryotes as they don’t contain introns
introns removed via splicing and exons are joined together to form mRNA
RNA translation
1-mRNA attaches to ribosome+ tRNA mols carry amino acids to it
2-complementary tRNA attaches to mRNA
3-2 amino acids joined by peptide bond (empty tRNA mol leaves)
4-process continues until stop signal
polypeptide is formed
types of mutation
insertion
deletion
substitution
what is a mutation
change in DNA base sequence of chromosomes
silent mutation
substitution can have no impact on amino acid due to degenerate nature of code
eg sickle cell anaemia
mutagenic agents
increases probability of random mutations (DNA being misread in replication)
eg radiation, carcinogens
chromosome non-disjunction
failure of chromosomes to separate properly in anaphase or meiosis eg Down’s Syndrome
intron mutations
affect what genes are turned on or off
meiosis steps
1-DNA unravels+ replicates 2-DNA condenses 3-homologous pairs line up 4-crossing over (recombinant chromosomes) 5-meiosis 1-homologous pairs separate 6-meiosis 2-sister chromatids separate
gamete variation due to…
crossing over of chromatids
-each contain chromatids w different alleles
independent segregation
-random chromosome assortment- variation in any offspring
meiosis vs mitosis
meiosis=
reduce chromosome number, 2 divisions, 4 daughter cells, cross over, genetically unidentical product
mitosis=
maintain chromosome number, 1 division, 2 daughter cells, don’t cross over, genetically identical product
