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Genetic Inheritance Patterns, Kinar 12B - Coggle Diagram
Genetic Inheritance Patterns
Sex determination
The process of determining an organism's sex based on inherited sex chromosomes
XY type
Found in humans, mammals, plants, and Drosophila melanogaster (fruit flies)
Females have two X chromosomes (XX) while males have one X and one Y chromosome (XY).
XO type
Found in insects like grasshoppers and aphids
Females have two X chromosomes (XX), while males have one X chromosome (XO)
ZW type:
Found in birds, moths, butterflies, and some fish
Males have two Z chromosomes (ZZ), while females have one Z and one W chromosome (ZW)
Haploid-diploid type:
Found in insects that undergo parthenogenesis, like honeybees
Males develop from unfertilized eggs and are haploid (n), while females develop from fertilized eggs and are diploid (2n)
Gene lingkage:
Occurs when genes close together on the same chromosome are inherited together
Results in fewer gametes and offspring with less phenotypic and genotypic variation compared to unlinked genes
example
Gene linkage in Drosophila melanogaster affects wing size and abdomen size, resulting in a 3:1 phenotypic ratio in the F2 generation
Pindah Silang
The exchange of genetic material between homologous chromosomes during meiosis
Produces new combinations of parental traits, resulting in recombinant gametes
Example: Crossing over in mango trees, producing four gamete types and a recombination frequency of 20%.
Factors influencing Pindah Silang
temperature: Temperatures above or below normal increase the likelihood of crossing over
Age: Older individuals have a lower chance of crossing over
Chemicals: Certain chemicals increase the likelihood of crossing over
X-rays: Exposure to X-rays increases the likelihood of crossing over
Distance between genes: Genes farther apart on a chromosome have a higher chance of crossing over
Gen letal: dominant/recessive genes that cause death when present in homogenous state
Dominant
Heterozygous individuals may exhibit abnormalities
Example
Creeper chickens. The dominant gene (C) in homozygous state (CC) is lethal. Heterozygous chickens (Cc) have short legs.
Yellow fur in mice. The dominant gene (Y) in homozygous state (YY) is lethal. Heterozygous mice (Yy) have yellow fur.
Brachydactyly in humans. The dominant gene (B) in homozygous state (BB) is lethal. Heterozygous individuals (Bb) have shortened fingers
Recessive
Heterozygous individuals are carriers
example
Albinism in corn plants. The homozygous recessive genotype (gg) results in albino plants that cannot produce chlorophyll and die
Ichthyosis congenita in humans. The homozygous recessive genotype (ii) causes severe skin abnormalities, leading to death in the womb or shortly after birth
Nondisjunction
The failure of chromosomes to separate properly during meiosis, resulting in gametes with extra or missing chromosomes
Can occur during meiosis I or II
Aneuploidy: A change in chromosome number affecting a specific chromosome pair. Can involve the addition or reduction of chromosomes.
Euploidy: A change in chromosome number affecting all chromosome pairs. The chromosome number becomes a multiple of the haploid number
Sex Lingkage
: The inheritance of traits linked to sex chromosomes
The X chromosome carries more genes than the Y chromosome, so sex-linked traits are primarily expressed in one sex
example
Eye color in Drosophila melanogaster. The gene for eye color is located on the X chromosome, resulting in white-eyed flies being predominantly male
Coat color in calico cats. The gene for coat color is located on the X chromosome, resulting in calico cats being predominantly female
Sex-linked traits in humans. dominant traits like brown teeth and hypertrichosis (excessive hair growth) and recessive traits like hemophilia, color blindness, and anodontia (absence of teeth)
Feather color in chickens. The gene for feather color is located on the Z chromosome, influencing the barred or non-barred feather pattern
Kinar 12B