Chapter 5 - Patterns Of Inheritance Flashcards
Gregor Mendel
The Father of Genetics
Austrian monk
First to make observations about inheritance patterns.
Genetics Definition
Is the study of inheritance
Why did Mendel used peas?
Many visible traits Easily reproduced (sexually and asexually)
Mendel Conclusions (3)
Each plant had two “factors” that act as sets of instructions for each characteristics.
Each parent donated one of these factors.
One factor or trait may be dominant over the other if present.
True Breeding Definition
Organisms that exhibit the same traits, generation after generation
P Generation Definition
(P = Parental) in breeding, the organisms initially crossed and are typically true breeding.
F Generation Definition
(F= first filial/son) the offspring of a cross of the P generation.
Monohybrid Cross Definition
(one mix = monohybrid) a cross of two individuals that differ by one trait.
Allele Definition
One of two or more different forms of a gene.
Dominant Definition
(Capital letter) The allele that is expressed regardless of the identity of the other allele.
Recessive Definition
(Lower Case) The allele that is only expressed when two alleles are present, or a trait that is hidden when the dominant allele is present.
Genotype Definition
(Like a chemical equations) The specific combination of alleles that an organism has for a trait.
Phenotype Definition
(Like a word equations) The physical description of an organism’s trait.
Homozygous Dominant Definition
Two dominant alleles (XX) Capital
Homozygous Recessive Definition
The recessive alleles (xx) Lower case
Heterozygous Definition
One dominant and one recessive allele (Xx)
Example of a Parent Generation
Genotype: PP x pp
Phenotype: purple x white
Example of F 1 Generation
Genotype: Pp Pp Pp Pp
Phenotype: Purple Purple Purple Purple
Example of F2 Generation
Genotype: PP Pp Pp pp
Phenotype: Purple Purple Purple White
Genes and Heredity Point
Your biological traits are controlled by genes located on the chromosomes that are found on/ in every cell of your body.
Garden Peas Replication
Self-fertilization and cross-fertilization
Mendelian Genetics
Came up with terminology: genes, alleles, dominant, recessive
Created a system of symbiosis to show traits (Letters)
Crossed two hybrid plants with round seeds from first generation.
Law of Segregation Definition
Separating of paired alleles during meiosis (formation of sex cells)
Mendel’s Law of Heredity Summary (3)
Each parent contributes are allele during fertilization (if purebred plat self fertilizes, each offspring receives two copies of the same allele)
The dominant allele is always expressed when recessive allele is present.
Each pair of alleles segregates during formation of sex cells.
Recap of Mendel
When organisms are crossbreed for a pair of contrasting traits, it shows only the dominant trait!
Definition of Punnett Square
A grid used to illustrate all possible genotypes and phenotypes of offspring from genetic crosses
Definition of Tess Cross
-Used when s genotype is unknown
-A cross between a parent of an unknown genotype with a homozygous recessive parent.
Eg. Needed to know whether individual is homo or heterozygous for tallness. (TT or tt)
Definition of Dihybrid Crosses
The inheritance of two traits
A cross of two individuals that differ in two traits due to two different genes
Example of Dihybrid Crosses
Crossing shape and colour at the same time Y_R_ 9:16 yyR_ 3:16 Y_rr 3:16 yyrr 1:16
Definition of Law of independent assortment
The alleles for one gene segregate or assert independently of the alleles for the other genes during gamete formation.
Definition of Pedigree
A flowchart that uses symbols to show the inheritance patterns of traits in a family over many generations (history of a trait between generation)
Definition of Autosome
Chromosomes 1-22 in humans. Non-sex chromosomes
Definition of Autosomal Dominant
The inheritance of a dominant phenotype whose gene is on an autosomal chromosome.
Definition of Autosomal Recessive
The inheritance of a recessive phenotype whose gene is on an autosomal chromosome.
Huntington disease
Autosomal dominant
Chromosome number 4
Neurological disease that results in a loss of muscle control and decline in mental ability.
Decreased life expectancy.
Cystic fibrosis
Autosomal recessive
Chromosome number 7
Causes thick mucus to build in the lungs, making breathing difficult and leading to infection
Blocks the pancreas, stopping digestive enzymes from reaching the intestines
Decreased life expectancy
Sickle cell anemia
Autosomal recessive Chromosome 11 Red blood cells are irregularly shaped Caused by an abnormal hemoglobin protein Decreased life expectancy
Phenylketonuria (PKU)
Autosomal recessive
Chromosome 12
Prevents the breakdown of phenylalanine, leading to developmental delays in cognitive function.
Must be treated immediately to avoid symptom development
Retinoblastoma
Autosomal dominant
Chromosome 13
tumours develop in the retina of young children
Fatal if not treated
Marian syndrome
Autosomal dominant
Chromosome 15
Affects connective tissue, leading to weakness in the heart, blood vessels, and skeleton.
Causes very long limbs
Increased susceptibility to heart and blood vessel conditions.
Tay-Sachs disease
Autosomal recessive
Chromosome 15
Progressive destruction of the nervous system caused by a lack of the enzyme hexosaminidase A, leading to the accumulation of lipids in the cells.
Fatal in early childhood
Niemann-Pick disease
Autosomal recessive Chromosome 18 Brain and nervous system impairment due to the accumulation of lipids in cells Decreased life span Type A fatal in early childhood
Maple syrup urine disease
Autosomal recessive
Chromosome 19
Inability to break down three amino acids, leading to nerve degeneration
Fatal if not treated
Adenosine deaminase deficiency causing severe combined immunodeficiency disease (ADA-SCID)
Autosomal recessive
Chromosome 20
Deviancy in the enzyme adenosine deaminase resulting in minimal immune response and susceptibility to all disease
Fatal if not treated with bone marrow transplant
Dominant allele criteria (3)
The trait is most likely transmitted by a parent to at least 50 percent of its offspring.
Depending on the size of the families involved, the trait will appear every generation.
If the allele is present, it will expressed phenotypically; in other words, in the appearance of the organism.
Recessive allele criteria (3)
Only homozygous recessive
The trait will occur in an offspring but may be absent in parents or other relatives.
Approximately 25 percent of the offspring will exhibit the condition of both parents are heterozygous for the trait.
Gene counsellor definition
A health- care professional with specialized training in medical genetics and counselling.
4 methods of genetic tests
Karyotype -chromosome structure and number
FISH(fluorescence in situ hybridization) - details of chromosomal abnormalities is based on visualizing, through fluorescence, a targeted region on a chromosome)
Gene testing- mutation(s) in the DNA sequence of a gene
Biochemical testing - abnormal enzymes and other proteins (often due to mutation of a gene that codes for the protein)
Gene Therapy definition
A technique aimed at correcting the effects of a mutated gene that is associated with a genetic disorder by inserting the correct form of the gene into the genome of the patient.
