Genetics 1 Flashcards
what does hereditary / inheritance refer to
what is happening to traits passed on or within multiple generations of a given family
what is the best way to follow inheritance patterns
family pedigree analysis
family pedigree standardised symbols:
what do the roman numerals down lhs mean
generation number (ie I will be at the top row, fourth row is 4th generation so IV etc)
family pedigree standardised symbols:
what do diagonal lines across a shape mean
individual has already died (so we don’t know if they’re affected or not)
family pedigree standardised symbols:
what do circles represent
females
family pedigree standardised symbols:
what do squares represent
males
family pedigree standardised symbols:
what does a plain circle or square represent
healthy individuals
family pedigree standardised symbols:
what does a filled in (ie in black) circle or square represent
diseased individuals
family pedigree standardised symbols:
what do dots or vertical stripes inside shapes / half shaded shapes represent
carriers of the disease (carry the defective gene but dont have the disease)
family pedigree standardised symbols:
how are twins symbolised
lines from parents make a triangle formation
family pedigree standardised symbols:
how are IDENTICAL twins symbolised
same triangle BUT they are also joined by a horizontal line between them
in what 5 ways can genetic information be passed from one generation to the next
1) human karyotype
2) chromosome structure
3) double helix
4) nucleobases and nucleotides
5) the genetic code
human karyotype:
what do chromosomes carry in eukaryotic cells
genetic information
human karyotype:
what is the normal karyotype for 1) males and 2) females
1) XY
2) XX
human karyotype:
how is genetic information passed on via this route
one chromosome in each of the 23 pairs is derived from mother and other from father
the dna of every chromosome records info that can be translated by the cells
chromosome structure:
during what stage of cell growth can we best observe condesnsed tightly packed DNA chromosomes
metaphase
chromosome structure:
what are the 3 steps of packing unwound structure of dna double helix into densely condensed chromosomes
1) dna wound around histone proteins (octamer) forming nucleosome
2) many nucleosomes look like ‘beads on a string’ = this is chromatin
3) regions of chromatin molecule interact and form chromatin fibres which are coiled and condensed to form chromosomes
the double helix:
which 2 scientists first described the double helix
watson + krick
base pairs are called watson-crick base pairs
the double helix:
what does it consist of
2 anti-parallel polynucleotide chains of specific chemical composition, held together by hydrogen bonding between pairs of nucleobases
the double helix:
what do nucleobases make up
the 4 letter code which encodes the genetic information
nucleobases and nucleotides:
what are the 2 types of nucleobases and what are they grouped based on
1) purine
2) pyrimidines
3) chemical structure
nucleobases and nucleotides:
list the purine bases
adenine
guanine
nucleobases and nucleotides:
list the pyrimidine bases
cytosine
thymine
uracil
nucleobases and nucleotides:
what is the structure of a nucleotide
a deoxyribose sugar with 1 phosphate and 1 nucleobase attached to it
nucleobases and nucleotides:
how are single nucleotides with different bases linked together into 1 sequence
phosphate group forms bonds with 2 ribose sugars
nucleobases and nucleotides:
how is the double helix formed
2 strands of antiparallel sequences of nucleotides bind to each other through hydrogen bonding
nucleobases and nucleotides:
what is the hydrogen bond pairing between the bases
adenine and thymine (or uracil in rna) = 2 H bonds
guanine and cytosine = 3 H bonds
(forms backup bc same info encoded)
the genetic code:
what can letters of nucleobases encoded in DNA be translated into
proteins (ie Val = valine)
the genetic code:
what does a codon translation table show
how cells interpret free nucleobases as a signal for each amino acid AND where to start / stop reading sequences
the genetic code:
what does the genetic code being redundant mean
several triplet codons code for the same amino acid
mutations can be silent (where a triplet changes so genetic code changes but new triplet still codes for the same amino acid)