Unit 8: Genetics And Heredity Flashcards
ABO blood type
classification of blood, based on presence or absence of antibodies, four major categories A, B, 0, and AB
Allele
one member of a pair of genes on specific chromosomes in specific positions
Aminocentesis
procedure which extracts fetal cells from the fluid surrounding the fetus, used to examine fetal chromosomes
Autosome
body chromosomes; in humans there are 44 autosomes (22 pairs) and 2 sex chromosomes XX or XY (1 pair)
Autosomal trait
any trait not dependent on the sex chromosomes
Blending theory of inheritance
the theory that offspring have a blend, or mix, of the characteristics of their parents.
Carrier
an individual that is heterozygous for a trait, they ‘carry’ the recessive allele, so that trait does not show up in the person but can be passed to their offspring
Chromosomes
a tightly wound bundle of DNA and proteins (histones) found in the nucleus
Codominance
when both alleles are expressed equally in the phenotype of the heterozygote, resulting in a phenotype that shows both traits of the parents; for example a black chicken crossed with a white chicken and the chicks are black and white checked.
Color blindness
a person with this recessive X-linked trait cannot distinguish between the colors red and green
Cross pollination
pollen from one plant fertilizes an other plant of the same species
Dominant allele
A dominant allele masks the expression of other alleles, for example brown eyes are dominant over blue eyes
Dihybrid cross
the cross between two plants that investigates two traits (for example plant with yellow round seed crossed with plant with green wrinkled seeds); a cross between two organisms that are each heterozygous for two traits of interest
F1 Generation
first filial generation* - the results of the cross between the two parent plants
F2 Generation
product of crossing the first set of offspring from an initial cross of parent organisms
Gametes
the reproductive cells: egg (female) or sperm (male)
Genetically modified organisms (GMO)
the reproductive cells: egg (female) or sperm (male)
Gene therapy
the introduction of cloned genes into living cells to replace an abnormal, disease-causing gene
Genetics
the science of heredity
Genome
total of all DNA sequences in a cell or organism; in humans it consists of approximately 3 billion base pairs, divided into thousands of genes on 23 pairs of chromosomes
Genotype
the alleles that are present in an organism for a trait, an organisms’ genetic makeup
Heredity
the passing of traits from parent to offspring
Heterozygous
having different pairs of genes for any given pair of hereditary characteristics, for example (Aa); also called a hybrid
Histone
protein that DNA wraps around to form the chromosomes
Homozygous
having identical pairs of genes for any given pair of hereditary characteristics, for example homozygous dominant (AA) or homozygous recessive (aa)
Hybrid
offspring of a cross between two purebred parents
Incomplete dominance
the phenotype of the offspring is somewhere in between the phenotypes of both parents; a completely dominant allele does not occur, a red flower crossed with a white flower produces pink flowers
Karyotype
picture of a person’s chromosomes, created by taking a picture of a dividing cell in the metaphase stage
Law of independent assortment
each pair of alleles segregates independently of one another during the formation of gametes
Linked genes
genes that are located on the same chromosome, so certain characteristics are innented together
Linkage map
shows the location of genes on a chromosome
Loci
plural term for position of a gene on a chromosome
Locus
position of a gene on a chromosome
Meiosis
the cell division process that creates egg and sperm cells (gametes)
Multiple alleles
genes that exist in three or more alleles in a population, for example blood types
Nondisjunction
failure of replicated chromosomes to separate during meiosis, resulting in gametes that are missing chromosomes or have extra chromosomes
P generation
‘Parent generation - the first set of individuals crossed with one an other, the
“parental” generation
Pedigree
a chart similar to a family tree, that shows how an inherited trait is passed through generations, squares represent males, circles represent females, shaded circle or square represents an individual that has a trait, and half shaded represents a carrier.
Phenotype
the observable traits of an individual, which are passed on from parent to offspring, such as height and eye color
Pollination
the transfer of pollen from the stamen (male) to the stigma (female) of flowers
Polygenic inheritance
characteristics that are controlled by more than one gene, and each gene may have two or more alleles, for example height and skin color in humans. The genes may be on the same chromosome or on non -homologous chromosomes.
Probability
likely outcome a given event will occur from random chance.
Punnet square
chart that allows you to determine the expected percentage of different genotypes in the offspring of two parents
Recessive allele
the genetic trait that only manifests itself (shows up) when two recessive alleles are present, represented by lowercase letters
Roan
color in animals that is an even mixture of white and another color such as red or black
Segregation
two factors (alleles) for a trait separate during gamete
Sex-linked genes
genes located on the sex chromosomes
Sex-linked traits
traits controlled by genes on the sex chromosomes (also called X-linked traits)
Traits
a characteristic or property of an organism, a genetically determined condition or characteristic (such as eye color)
Transgenic organism
an organism that expresses genes that were introduced from a different organism
X-linked genes
genes located on the X chromosomes
X-linked traits
traits controlled by genes on the sex chromosomes (also called sex-linked traits)
