Heredity Flashcards
Condensed DNA allowing genetic code to be passed down to generations
chromosomes
unit of genetic material encoding a trait
gene
alternative forms of a gene
allele
the physical location on the chromosome where the gene resides
locus
containing two complete sets of chromosomes
diploid
containing one complete set of chromosomes
haploid
diploid, non reproductive cells; mutations not passed to offspring
somatic cells
located in testes and ovaries, and undergo meiosis to produce gametes; are diploid and mutations are passed to offspring
germ cell
sex cells that are haploid and combine to form diploid zygotes; mutations are passed to offspring
gamete
genetic component of inheritance; combination of both alleles from parents
genetic component of inheritance
physical trait displayed arising from genetic component
phenotype
A trait that is expressed no matter what the other trait is
dominant allele
Only expressed if there is no dominant allele is present
recessive allele
Same allele type from father and mother
homozygous
different alleles from father and mother
heterozygous
having only a single copy of a gene instead of two; usuall y in males due to one x and one y chromosome
hemizygous
says that the gametes of an organism will only carry one allele for each gene
law of segregation
says that different homologous chromosome pairs separate independently of one another; results in very diverse offspring
law of independent assortment
says that a dominant allele masks the effect of a recessive allele
law of dominance
The parental generation is usually a ___ __ crossed against a ___ __, or a __ ___ cross, which results in all heterozygous offspring
homozygous dominant, homozygous recessive, true breeding
The ______ generation is the first generation of offspring and is the result of breeding parental organisms. It usually guarantees all ___ offspring or ____
F1, heterozygous, monohybrids
The ___ is the second generation of offspring and usually comes from crossing the F1 generation with itself. usually the ratio is ______
F2, 1:2:1
Cross between heterozygotes for 2 particular traits
dihybrid cross
Test cross of heterozygotes used to look at inheritance of one set of alleles
monohybrid cross
To make a dihybrid cross, first two ___ __ parents must be bred. Then the resulting ____ offspring are bred together. The dihybrid cross confirmed the law of __ ___
true breeding, heterozygous, independent assortment
The phenotypic ratio for a 2 heterozygous parents offspring is
9:3:3:1
when an organism with an unknown genotype is crossed with a homozygous recessive organism
test cross
When there is more than one dominant allele, and a heterozygous individual will show a blend between the phenotypes of the homozygotes
incomplete dominance
When both inherited dominant alleles are completely expressed
codominance
When there are more than two possible alleles for a genes (e.g. blood type, eye colour)
multiple alleles
When one gene’s expression affects the phenotypic expression of another
epistasis
When a single gene affects multiple phenotypic traits
pleiotropy
The interaction of many genes that shapes one phenotype; tends to be traits that are on a spectrum (e.g. skin colour and height) and are often in a bell curve distribution in the population
polygenic inheritance
genes that are on autosomal genes (e.g. gene for sickle cell anemia)
autosomal gene
Gene that is carried on the X or Y chromosome
sex linked genes
Most chromosomes are located on the ___ chromosome, for example for ____. Men only have one x chromosome, so they will express the gene with only one __ ___. __ ___ gene resides on the y chromosome
X, colourblindness, affected allele, webbed toes
Someone that is heterozygous for a recessive allele
carrier
Men cannot be ___ for X linked diseases, and must have inherited from their ___
carriers, mothers
When expression is influenced by the sex of the individual carrying the trait; ex. baldness gene
sex influenced gene
When allele expression is affected by which parent it came from; affects autosomal chromosomes; turning off or on of selective genes
genomic imprinting
The probability that an organism with a specific genotype will express the corresponding phenotype
penetrance
Describes the variation of a phenotype of a specific genotype; the amount of expression
expressivity
a female phenomenon in which one of the two x chromosomes is condensed into a barr body that is not expressed; random
x inactivation
Turner’s syndrome is due to a complete or partial absence of a ___ ___. This disease occurs because not all genes on the __ __ are inactive. Some are kept active and without those, the individual cannot function. ____ between chromosomes are necessary for healthy functioning
x chromosome, barr body, interactions
When the heterozygous genotype has a higher relative fitness than homozygous dominant or recessive individuals (ex. sickle cell disease and malaria resistance)
heterozygote advantage
When two or more genes reside physically close to one another and are inherited together
linked genes
linked genes manifest in the __ __ that occurs during __ __. The closer the genes are physically on the chromosomes, the __ likely they are to be separated by crossing over. Gene linkage determines whether or not different genes on the same chromosome will end up going to __ ___
crossing over, meiosis I, less, different gametes
The likelihood that two genes will be separated by crossing over; the closer the genes, the lower the likelihood
recombination frequency
The highest recombination frequency of two genes is ____%
50
Diagram that represents a family tree to show the occurrence of heritable traits over multiple generations
pedigree
Unaffected parents having an affected offspring is indicative of a ___ allele
recessive
Autosomal dominant pedigree charts do not ____ generations, but the affected parents can be ____ offspring, if both are ___. Males and females are __ __. An example is ___ ___
skip, unaffected, heterozygotes, equally effected, huntington’s disease
Autosomal recessive pedigree charts can ___ generations, and 2 unaffected parents can have __ ___. Males and females are both equally affected, and an example is __ ___
skip, affected offspring, cystic fibrosis
X linked dominant pedigree charts will never have two unaffected parents having ___ offspring. The trait is never passed from the __ to ___. All ___ of an affected father will get the trait. Sons of an affected____ may or may not have the trait. The gene is dominant so males and females are __ ___
affected, father, son, daughters, mothers, equally affected
In X linked recessive pedigree charts, the trait can only be passed on from __ to ___ but never __ to ___. A normal father will never have an affected ____, but affected mothers will always have affected ___. It can __ generations, and ___ are more frequently affected. Examples include ___ __ and ___
mother, son, father, son, daughter, sons, skip, males, colour blindness, hemophilia
When close relatives mate together, it results in ___ pedigree charts, and increase in the likelihood of a _ ___ appearing. __ ___ line indicate inbreeding
consanguinity, recessive conditions, double line
Problems that can be caused by mutations, environmental factors, or other damage to chromosomes
genetic defects
A mutation that occurs at the level of a single nucleotide
point mutation
point mutation that results in a shift of the reading of the codon
frameshift mutation
point mutation that results in the shift of a purine for another purine or pyramidine for another pyramindine
transition mutation
mutation in which purine nucleotide is converted to a pyramidine or vice versa
transversion mutation
mutation that changes a wild type allele to mutant allele
forward mutation
mutation that changes a mutant allele back to a wild type allele
backward mutation
when chromosomes do not separate during mitosis or meiosis
non disjunction
___ can occur in cells that undergo mitotic nondisjunction during __ ___. This is when a fraction of the body cells have __ or __ chromosomes. this can also occur as a result of __ ___
mosaicism, mitotic nondisjunction, embryonic development, extra, missing, nucleotide mutations
Meiotic non disjunction results in gametes with __ or extra chromosomes. _______ is when there are 3 copies of a chromosome and ____ causes down syndrome. ___ is when there is only one copy of the chromosome. This nondisjunction can occur in ___ or ___
missing, trisomy, trisomy-21, monosomy, meiosis I, meiosis II
When an organism has extra or missing chromosomes
aneuploidy
___ is the process of visually examining the full set of an organism’s chromosomes to evaluate ___. it is performed during the ___ of the cell cycle and allows you to identify the __, __ and __ of the chromosomes. ___ and _______ syndromes can be detected from this
karyotyping, abnormalities, metaphase, number, size, shape, down, turner’s
When two chromosomes swap segments; resulting in different sizes and banding patterns
translocations
when a chromosome segment is repeated on the same chromosome resulting in a longer chromosome
duplication
when a chromosome segment is rearranged in the reverse of its original orientation
inversions
when part of one chromosome is moved to a different chromosome
substitution
when part of one chromosome is lost and the chromosome is shorter
deletion
the physical break in chromosomes that can result in deletions, rearrangements, translocations, etc.
chromosomal breakage
Normally, __ stimulate normal growth, but if mutated becomes a ____, which cause cancer. One example is the ___ gene
proto-oncogenes, oncogenes, ras
_____ genes prevent cells that dividing excessively. If mutated to __ activity, it can contribute to cancer formation. An example is the ___
tumor-suppressor, decrease, p53
Viruses can also cause cancer by ___ with the host genome. This can disrupt the genes responsible for regulating __ ___, and disruption of the __ __
integrating, normal growth, cell cycle
Substances that cause cancer
mutagenic agents
Mutagenic agents include ____ rays, ___ rays, ___, chemicals like ____, ___ smoke, ____ ___and _ ___, as well as ___ ____ and ____.
cosmic, x, nitrate, cigarette, mustard gas, benzoyl peroxide, human paillomavirus, helicobacter pylori
__ prevents unregulated cell growth by preventing the stabilization of _____ ____ during cell division. _____ drugs kill off rapidly dividing cells
cholchicine, mitotic spindles, chemotherapeutic
Autosomal dominant conditions include ___ disease (NS degeneration), _____ (dwarfism), and ____ (excess cholesterol in the blood that progresses to heart disease)
huntington’s, achondroplasia, hypercholesterolemia
Autosomal recessive conditions include _____ (phenylalanine breakdown instability) ___ ___ (fluid buildup in respiratory tracts), __ disorder (inability to breakdown lipids, affecting brain function), _____ ____(defective hemoglobin), and _____ (inability to breakdown galactose)
phenylketonuria, cystic fibrosis, tay-sachs, sickle-cell anemia, galactosemia
Sex linked recessive conditions include ____ (abnormal blood clotting), __ ___, and ___ __ __ (a progressive loss of muscle)
hemophilia, colour blindness, duchenne’s muscular dystrophy
Aneuploidy disorders include __ syndrome (extra 21 chromosome), ___ syndrome (missing X chromosome), ____ syndrome (extra X chromosome), ___ _ ___ syndrome (piece of chromosome 5 missing)
down, turner, klinefelter’s, cri du chat
___ ___ is due to the fact that genes exist outside the nucleus in eukaryotes in the __ and ___. Defects in mitochondrial DNA can reduce a cell’s ___ production and all of the defects are ___ inherited
extranuclear inheritance, mitochondria, chloroplasts, ATP, maternally
Genes that prevents the survival of an organism
lethal allele
Gene that when mutated in the mother, results in a mutant phenotype in the offspring regardless of the offspring’s genotype
maternal effect gene
Maternal effect genes result because of maternal defective products in the __ such as ___ or ___.
egg, mRNA, proteins
