Chromosomes & Genomes Flashcards
What do DNA wrap around and form when making chromosomes?
His tone protein and it forms a nucleosome
What are chromosomes?
Thread-like structures composed of DNA and protein, and visible in the cells during mitosis and meiosis
A cell with one set of chromosomes are…
…haploid
A cell with two sets of chromosomes are…
…diploid
A cell with many sets of chromosomes are…
…polyploid
What is the short arm of a chromosome called?
p (petite)
What is the long part of the chromosome called?
q
What are the short and long arm held together by?
Centromeres
Do every chromosome have the same size and shape?
No, no two non- homologous chromosomes have the same size or shape
Name three chromosomal changes that can occur.
Duplication
Deletion
Inversion
What happens in a duplication chromosomal change?
Part of the chromosome is repeated
What happens during a deletion chromosomal change?
Part of the chromosome is deleted
When does the chromosomal changes of deletion and duplication occur?
Cross-over in mitosis (Prophase 1)
What happens in a inversion chromosomal change?
Reverses part of the chromosome
What is translocation?
When part of a chromosome is transferred to another
What is non-reciprocal translocation?
Result in one chromosome with a deletion and the other with an addition
What is reciprocal translocation?
When a part of a chromosome is added to another but the original chromosome isn’t changed
What is it called when a whole chromosome arm is translocated?
Robertsonian Translocation
Why do humans have one less chromosome than the rest of the great apes?
Due to a translocation of two chromosomes during the evolutionary history of humans AFTER they diverged from their last common ancestor with the chimps
What is a karyotype?
Karyotypes are the conventional way of organising chromosomes to assist in analysis
What are homologous chromosomes?
Homologous chromosome pairs are identified by size and the location of their centromere!
How are homologous chromosomes identified?
Same size, shape and banding pattern
What does the karyotype of humans consist of?
23 pairs of chromosomes.
22 pairs of homologous autosomes
1 pair of sex chromosomes
What is trisomy?
When you have three chromosomes instead of the normal two
What is monosomy?
When you have one chromosome instead of the normal two.
How does trisomy occur?
Results in one gamete having two copies of a chromosome, and one gamete having no copies of the chromosome
How many sex chromosomes are there?
2
X Chromosome
Y Chromosome
What determines a male?
The SRY gene on the Y chromosome
What is a genome?
All of the genetic information (the base pairs) found in one complete set of an organisms chromosomes.
Can there only be one genome?
No, mitochondria and chloroplast have set of chromosomes too.
There can be mitochondrial genome and chloroplast genome
The study of genomes is called?
Genomics
Does the size of a genome determine the complexity of an organism?
No it does not
What is so important about genomes?
The power of genomes comes from comparing the similarities and differences in the genomes of different species
What is the study of comparing genomes?
Comparative genomics
How can comparative genomics be useful?
Comparative genomics is a useful tool in studying evolutionary relationships between different organisms
