| How is DNA organised in nucleus? | chromosomes |
| What is a gene? | a heritable factor that has a DNA length and influences a specific trait |
| What is a locus? plural form? | position of a gene on a specific chromosome
loci |
| What is an allele? how do they differ? (3) | different forms of a gene that codes for different versions of a trait
have very similar gene sequences
only differ by few bases
eg: brown eye color and blue eye color are 2 different alleles |
| What is a mutation? | a change in nucleotide sequence of a DNA section |
| How are new alleles formed? | by mutation |
| What are the 3 categories of gene mutations? | Beneficial
Detrimental
Neutral |
| What are beneficial mutations? | missense - changes the DNA sequence to make new variations of a trait |
| What are detrimental mutations? | nonsense - shorten gene sequence which affects the normal function |
| What are neutral mutations? | silent - no effect on the feature |
| What is sickle cell anemia? | caused by base substitution on the 6th codon of beta chain of hemoglobin |
| What are the steps of sickle cell anemia base substitution? | DNA: GAG = GTG (non transcribed)
DNA: CTG = CAC (Transcribed)
MRNA: GAG = GUG (Identical to non transcribed)
Polypeptide: glutamic acid = valine |
| What are the problems caused by sickle cell anemia? (4) | forms insoluble fibrous strands =
affects how much oxygen can be carried = tiredness and anemia
strands can block capillaries forming clots bec of sickle shape
sickle shaped blood is destroyed more easily |
| How does the shape of SCA change? | bioncave = sickle shaped because it forms insoluble fibrous strands |
| what is the genome? | total genetic info of an organism |
| How many chromosomes do humans have? | 46 |
| What is the HGP? | Human genome project sequenced the human genome by
mapping
screening
meds
ancestry |
| what are the 4 ways HGP has sequenced the human genome? | mapping = number and size of sequences
screening = gene probes to detect genetic diseases
medicine = new proteins discovered led to better treatment
ancestry = insight into evolution |
| what is the link between no of genes and biological complexity? | differs between species but a greater number of genes doesn't mean greater biological complexity |
