L11- DNA introduction Flashcards
DNA is found in the nucleus packaged into
chromosomes
heterochromatin
condensed- darker
- genes not expressed
euchromatin
uncondensed- light
- genes expressed
DNA is made up of
genes
central dogma
DNA–> RNA –> proteins
genes in the nucleus encode proteins found in the cytoplasm
how many m of DNA in each cells and what’s its width
2m, 6um
width of DNA helix
2nm
linear DNA (DNA helix) is packaged first by
wrapping its self around histone core twice (nucleosome)
nucleosome
histone with DNA wrapped around twice
nucleosomes are linked by
linker DNA and look like beads on a screen
beads on a screen
euchromatin
beads on a string packaged tighter into
solenoid
solenoid
- 30nm fibre (heterochromatin- genes not expressed)
solenoids loops form to create
chromosomes
- no gene expression not accessible for transcription e
one chromosome=
one DNA molecule
one chromosome after replication
2 DNA molecules connected by a centromere
end of chromosomes called
telomeres
smaller arms
p arm
longer arms
q arms
a gene is a
stretch of DNA that codes for a protein
genes are located on
the chromosomes in a fixed location
- diff genes have diff chromosomal locations
how many genes carried on chromosomes
25,000
how many pairs of chromosomes do humans have
23 pairs (sex chromosomes are a pair) - 46 overall
nucleic acid=
linear polymers of nucleotides (polynucleotides)
- negatively charged due to phosphate groups
what makes up a nucleotide
base + sugar (phosphate). + phosphate
difference between ribonucleic and deoxyribonucleic acid
ribonucleotide has two hydroxyl group
deoxyribonucleotide has one hydroxyl group
ribonucleic acid
forms RNA
- ribose as sugar