3.2 Flashcards
Homologous chromosomes are chromosomes that share:
- the same structural features
- the same genes at the same loci positions
Which chromosome is shorter out of the X & the Y
the Y chromosome
Two ways a karyogram can be used:
- to deduce sex
- to diagnose Down Syndrome (trisomy 21)
Features of plasmids
- Naked DNA - not associated w histone proteins
- Small circular rings of DNA
- Not responsible for normal life processes
- Commonly contain survival characteristics -e.g antibiotic resistence
- Can be passed between prokaryotes
- Can be incorporated into the nucleoid chromosome
How can chromosomes vary?
- length - number of base pairs in DNA molecule
- position of the centromere
- genes occur at a specific locus
What is the N number
number of chromosomes possessed by a species
How many chromosomes do humans have?
23 different chromosomes
Diploid nucleus
Has 2 of each chromosome - therefore have 2 copies of every gene
Haploid nucleus
Has 1 of each chromosome
What type of nuclei do gametes have?
Haploid nuclei
Which type of nuclei are less susceptible to disease?
Diploid nuclei - have 2 copies of gene so organism is more likely to possess a healthy copy
How many diploid chromosomes in each human cell?
46
Are body cells (somatic cells) haploid or diploid?
diploid
How human chromosome pairs are homologous?
22
Why is X bigger than the Y?
X carries many genes in the non-homologous region which are not present on Y
