Unit C2: Cell division, genetics, and molecular biology Flashcards
Crossing-over
- Occurs between non-sister chromatids during meiosis.
- Creates four types of gametes in a dihybrid instead of two.
- Produces recombinant gametes with new gene combinations.
- Helps determine gene order on a chromosome.
Happens more often between distant genes than closer ones.
Dihybrid
An organism heterozygous for two genes, producing four types of gametes.
independent assortment
Genes on different chromosomes separate randomly during gamete formation.
locus linkage group
Locus: The specific location of a gene on a chromosome.
Linkage Group: Genes located on the same chromosome that tend to be inherited together.
autosomes
Non-sex chromosomes that are the same in both males and females.
carrier
An individual who has one recessive allele for a trait but does not express it.
colour blindness
A genetic condition where an individual has difficulty distinguishing certain colors, usually red and green.
Duchenne muscular dystrophy
A genetic disorder causing progressive muscle weakness, primarily affecting boys, due to a mutation in the dystrophin gene.
hemophilia
A genetic disorder where blood doesn’t clot properly, leading to excessive bleeding from injuries, caused by a deficiency in clotting factors.
sex chromosomes
Chromosomes that determine an individual’s biological sex; XX for females and XY for males.
X-linked genes
Genes located on the X chromosome, often affecting males more since they have only one X chromosome.
Y-linked genes
Genes located on the Y chromosome, typically determining male traits and passed from father to son.
Down syndrome
A genetic disorder caused by trisomy 21 (an extra copy of chromosome 21), leading to developmental delays and characteristic physical features.
karyotype
A visual representation of an individual’s chromosomes, arranged by size and shape, used to detect genetic abnormalities.
Klinefelter syndrome
A genetic condition in males caused by an extra X chromosome (XXY), leading to symptoms like reduced fertility, less muscle mass, and learning difficulties.
monosomy
genetic condition where an individual is missing one chromosome (2n - 1), often leading to developmental disorders.
nondisjunction
The failure of chromosomes to separate properly during meiosis, leading to gametes with extra or missing chromosomes.
polyploidy
A genetic condition where an organism has extra sets of chromosomes (e.g., 3n or 4n), common in plants but rare in animals.
trisomy
A genetic condition where an individual has an extra chromosome (2n + 1), leading to disorders like Down syndrome (trisomy 21).
turner syndrome
A genetic disorder in females caused by a missing or incomplete X chromosome (XO), leading to short stature, infertility, and developmental differences.
adenine
Adenine (A): A purine nitrogenous base in DNA and RNA that pairs with thymine (T) in DNA and uracil (U) in RNA through two hydrogen bonds.
antiparallel
The two strands of the DNA double helix run in opposite directions—one 5’ → 3’, the other 3’ → 5’—allowing for proper base pairing and replication.
complementary bases
Nitrogenous bases in DNA that pair specifically through hydrogen bonds—Adenine (A) pairs with Thymine (T) (2 bonds), and Guanine (G) pairs with Cytosine (C) (3 bonds).
cytosine
A pyrimidine nitrogenous base in DNA and RNA that pairs with guanine (G) through three hydrogen bonds.