DNA and RNA Flashcards
define gene
a section of DNA that causes the production of a protein
what are chromosomes made of
DNA + protein
how much DNA is used for coding proteins
3%
what is junk DNA
non coding DNA
where are chromosomes found
nucleus
when chromosomes are not dividing what do they form
chromatin
what form of bonding holds DNA together
hydrogen bonds
what is a nucleotide composed of
phosphate + base + sugar (deoxyribose)
what are pyrimidines
single ring shaped molecule (thymine and cytosine)
what are purines
double ring shaped molecule (adenine and guanine)
what base differs in DNA than RNA
RNA has uracil rather than thymine
what is a codon
a triplet of bases e.g CAA codes for Valine
explain DNA replication
double helix unwinds, enzymes break down hydrogen bonding, free floating nucleotides in the cytoplasm enter the nucleus and attach to complimentary base pairs… creates a new DNA strand which rewinds to form a new double helix
what is DNA profiling
a method of making a unique pattern of bands from a person’s DNA which can be compared to another person’s DNA
what can DNA profiling be used for
crime; biological evidence can be compared to suspect. can be used in medical, paternity and maternity tests
describe the process of DNA profiling
DNA is released from cells, cut into different sized fragments using restriction enzymes, fragments are separated by their size by a process called gel electrophoresis which produces a unique pattern in the gel, patterns are then stained and compared
what is genetic screening
testing DNA for the presence/absence of a particular of a particular or an altered gene
what sort of diseases might be tested for using genetic screening
sickle cell anemia, cystic fibrosis, hereditary cancers
explain protein synthesis
enzymes unwind and unzip the DNA to expose the compimentary base pairs. transcription then occurs- RNA nucleoides move from cytoplasm and join to the exposed complimentary base pairs. RNA polymerase joins the bases together to form mRNA. mRNA goes to ribosomes and forms a weak bond with rRNA . tRNA moves into ribosome and brings amino acids with it + attaches to mRNA after the start codon. tRNA leaves ribosome and pulls mRNA strand through the ribosome. this continues until a protein is formed. proteins are then folded into the correct shape
