Ch 1 Flashcards
Whats DNA
helical double stranded molecule containing genetic material holding the information for all cell function
where’s DNA found in eukaryotes
nucleus, chloroplasts and mitochondria
what’s DNA composed of
nucleotide base pairs which contain
- 5 carbon deoxyribose sugar (ribose in RNA)
- phosphate group
- nitrogenous base
wok discovered DNA
James Watson & Francis Crick
what are the 4 nitrogen bases
guanine
cytosine
thymine (uracil in RNA)
adenine
what direction does DNA/RNA run
5’ to 3’
What does DNA helicase do
its an enzyme that unzips the double stranded DNA by breaking the weak H-bonds between the nucleotides
replication fork
the point where the unwound DNA and the intact DNA helix meet
what does DNA polymerase do
attaches free-floating nucleotides to the exposed bases (A/T and C/G)
what does DNA ligase do
seals the new stretches of nucleotides into a continuous strand
what’s the first step of DNA replication
Double helix is unziped and unwound to act as a template for two new DNA strands or double helixes
what does semi-conservative replication mean
1 strand of DNA is retained/conserved while the other is new.
When does DNA replication occur
during interface of mitosis
where DNA found in prokaryotes
unbound circular DNA in the nucleoid (a region where chromosomes can be found) in their cytosol
true or false DNA coils around histone proteins and are linked at a point called centromere
True
what’s a karyotype
the standard form used to display and analyse chromosomes
compare diploid and haploid
diploid (2n) – having 2 complete sets of chromosomes e.g somatic cells
haploid (n) – having a single set of unpaired chromosomes e.g. gametes
define locus/loci
the location of a particular gene on a chromosome
define allele
the alternative forms of the same gene e.g hair colour being black or brown
plasmid
a single circular chromosome (DNA) within the cytoplasm
