chromosomes & genes Flashcards
1
Q
Somatic cells
A
46 chromosomes or 23 pairs of chromosomes
New cells arise from mitosis
2
Q
Germ cells
A
23 chromosomes
New cells arise from meiosis
3
Q
Homologous chromosomes
A
- code for the same gene
- first 22 are autosomal + homologous
4
Q
Ploidy
A
no. of chromosomes
5
Q
DNA
A
- coiled around proteins (histones)
- Most of the time in “uncoiled” state
- Allows machinery in the cell to access genes along the DNA sequences to make proteins
6
Q
Genes
A
- sections along DNA that code for proteins
- The same gene is found at the same location (locus) on homologous chromosomes
7
Q
Alleles
A
- variants of a gene
- Proteins made are slightly different
8
Q
Genotype
A
combination of alleles for a particular gene
* Homozygous (alleles are all the same)
* Heterozygous (alleles are different)
9
Q
Phenotype
A
observable or measurable trait that is the consequence of the interplay between the genetic makeup and environment factors
10
Q
Dominant Alleles
A
- Mask the effect of recessive
- Not about preferential expression
- Nor are the alleles necessary more common in a population
- Not necessarily the “normal” allele
11
Q
Recessive Alleles
A
- Effect masked by dominant
- The allele of a gene can be expressed normally but the protein does not work well
- But sometimes the recessive allele codes for the “normal” protein
12
Q
Codominance
A
when 2 different phenotypes are expressed equally
13
Q
Incomplete dominance
A
gives rise to a phenotype that is intermediate between the dominant and recessive phenotypes
