The human genome and chromosomes Flashcards
why is the human genome useful
- Useful for understanding the structure of genomes
- Understanding the biology of genomes
- Understanding the biology of disease
- Advancing the science of medicine
- Improving the effectiveness of healthcare
describe the structure of the nuclear genome
- 3.2x109 base pairs
- 20,000 protein coding genes
- 46 chromosomes
- Inherited from both parents
how many chromosomes does each somatic cell have
Each somatic cell has 46 chromosomes which are mostly clearly seen at the metaphase stage of the cell cycle
how can you identify chromosomes in the karyotype
using G bands
what are G bands
- staining technique used in karyotype, used to identify abnormalities in the chromosome
what is the short arm called (above the centromere) in the chromosome
p
what is the long arm called (below the centromere) in the chromosome
q
what does the centromere do and describe the structure
- Keeps sister chromatids together
- Attaches sister chromatids to microtubules
- Repetitive DNA
- Breaks during DNA replication
What does the G light band do and describe the structure
- Gene rich – has lots of genes compared to the dark ones which have a few genes
- GC-rich – lots of G and C nucleotides
- Early replicating
What does the G dark band do and describe the structure
- Gene poor
- AT rich – lots of A and T nucleotides
- Late replicating
what is an autosome
any chromosome that is not a sex chromosome and occurs in pairs
what are the sex chromosomes
XX female
XY male
what does diploid mean and how many chromosomes are in diploid cells
describes cells and nuclei or organisms in which each chromosome except the Y chromosome is represented twice
what does haploid mean and how many chromosomes are in haploid cells
Haploid are organisms that have a single set of unpaired chromosomes
what does aneuploidy mean
this is an abnormal number of chromosomes
Name the genes that you need to know
- COL5A2 (2) - collagen
- COL5A1 (9) – collagen
- HBA1 (16) - alpha globin for haemoglobin
- HBA2 (16) - alpha globin for haemoglobin
- BTK (x) - crucial role in B cell development
What are coding sequences
encode proteins, constitute about 1.6% of human genome
what are non-coding sequences
encode other molecules (such as tRNA and rRNA) and regulates coding DNA function. Encode intergenic regions and introns: include control elements (such as enhancers and promoters) and repetitive sequences (telomeres)
what are axons
regions of gene that encode protein sequences
what are introns
non coding regions between the exons in genes
what are control elements
sequences such as promoters and enhancers that regulate transcription
what are pseudogene
– non-functional copy of a gene, arises from gene duplication followed by deleterious mutation in one copy