3.1,3.2,3.3,10.1 Flashcards
(26 cards)
A gene occupies ______
A specific position on a chromosome
Define gene
A heritable factor that consists of a length of DNA and influences a specific characteristic
Allele
Various specific forms of a gene
How are new alleles formed?
Mutation
Genome
The whole of the genetic information of an organism
Causes of sickle cell anemia
- base substitution mutation
- change to the base sequence of mRNA transcribes from it
- change to the sequence of a polypeptide in hemoglobin
How many chromosomes do prokaryotes have?
One consisting of a circular DNA molecule
Something some prokaryotes have but eukaryotes do not
Plasmids
Homologous chromosomes carry what?
The same sequence of genes but not necessarily the same alleles of those genes
Diploid nuclei -
Paired of homologous chromosomes
Haploid nuclei-
One chromosome of each pair
Genome size-
Total length of DNA in an organism
Karyotype
Number and type of chromosomes present in the nucleus
Karyogram
Photograph or diagram of karyotypes
Considered sister chromatids until when?
The splitting of the centromere at the start of anaphase. Then they’re individual chromosomes.
The halving of the chromosome number allows
A sexual life cycle with fusion of gametes
Genetic variation promoted by:
Crossing over
Random variation
Fusion of gametes
Description of methods used to obtain cells for a karyotype analysis.
- sample of cells
- cells placed in a laboratory dish and allowed to grow.
- the non-divided cells are separated from the dividing cells using special chemicals
- cells are treated with a chemical which stops cell division at the point where the chromosomes are the most compact.
- In order to be able to tell one chromosome from another, a special dye called Giemsa dye is applied to the chromosomes on the slide
- a picture is taken of the cells while they’re in mitosis
- then the chromosomes are analyzed
When do chromosomes replicate?
Interphase before meiosis
Crossing over
Exchange of DNA material between non-sister homologous chromatids
Crossing over produces:
New combos of alleles on the chromosomes of the haploid cells
Chips maya formation between non-sister chromatids can result in:
An exchange in alleles
When do homologous chromosomes separate?
Meiosis 1
When do sister chromatids separate?
Meiosis 2