Genetics Flashcards
Heredity
The passing of traits from parent to offspring
Describe the law of dominance….
Some traits can mask other traits when both traits appear in the parents.
Ex: Red is dominant to white
Describe the law of segregation…..
During the formation of reproductive cells (sperm, egg) the paired factors (genes) separate from one another and then recombine.
Describe the law of independent assortment…
Each trait is inherited independent of one another
Exception: blond hair, blue eyes
Factor-
Gene-
Allele-
Describing a gene (mendels word)
Trait
A form of a trait
Describe incomplete dominance….
The two alleles are neither dominant or recessive. Both contribute to the phenotype of the offspring. (Blending)
Ex: Snap dragons
Describe co-dominance and multiple alleles….
Two alleles may contribute equally in the offspring and are both dominant. (No blending)
Example: speckled chicken produced from a black chicken and white chicken.
Or blood types (Type AB has both A and B)
Describe sex linked traits….
All organisms that reproduce sexually have a combination of X and Y chromosomes.
Male: XY Female: XX
Acquired trait
Inherited trait
Trait that has been learned
Ex: scars, attitude
Trait passed from parent to offspring (or from ancestor)
Ex: eye colour
Autosome
Non sex chromosome
Carrier
A female that carries a gene but does not express it in her phenotype.
Ex: Hemophilia (XRXr)
Chromosome
Threadlike structure carrying genetic information in the form of genes
Diploid
A cell that contains two sets of homologous chromosomes
Fertilization
During sexual reproduction, an egg and sperm combine to form a zygote
Gamete
Sex cell (sperm or egg)
Genotype
Symbolic representation of a characteristic
Haploid
A cell that contains only a single set of genes
Heterozygous
Having two different alleles for a particular gene
Homologous
Chromosomes in which one set comes from the male parent and one set from the female parent
Homozygous
Having two identical alleles for a particular gene
Karyotype
Micro graph showing the number and visual appearance of the chromosomes
Meiosis
Cell division that results in 4 daughter cells each with half the chromosomes as the parent.
Formation of gamers
Multiple alleles
3 or more alternative forms of a gene
Non disjunction
Failure of homologous chromosomes or sister chromatids to separate during cell division.
Phenotype
Physical characteristic of an organism
Pedigree
Diagram that shows the occurrence and appearance or phenotype of a genetic trait from one generation to the next within a biological family
Test cross
Genetic cross between homozygous recessive and a suspected heterozygous to determine the genotype of the later.
Tetrads
4 chromatids in groups of 2 formed in prophase 1
Synapsis
Fusion of chromosome pairs at the start of meiosis that enables crossing over to occur
Cystic fibrosis cause and symptoms
Autosomal recessive Inherited disease passes a defective gene that causes buildup of thick mucus that can damage organs. Clogs lungs and is associated with digestive problems.
Down syndrome causes and symptoms
Nondisjunction causes an extra chromosome 21 which leads to cognitive impairment, flattened facial appearance and upward slanted eyes.
Hemophilia causes and symptoms
Sex linked trait that can lead to lack of blood clotting proteins. This creates excessive bleeding.
Kleinfelter’s syndrome causes and symptoms
Due to non disjunction a big is born with an extra X chromosome resulting in small testicles, breasts and reduced muscle mass.
Marfan syndrome causes and symptoms
Autosomal dominant: Mutation of gene that makes fibrin (protein in connective tissue) inherited from one parent. Leads to disproportionate legs and arms, heart murmurs, tall and slender build
Turners syndrome
A female with only 1 X chromosome due to non disjunction. Girls affected are short, infertile and have heart defects.
Huntington’s
Autosomal dominant disorder causing progressive breakdown of nerve cells in the brain. Leads to uncontrollable movements, difficulty with speech, lack of awareness
Sickle cell disease
Autosomal recessive disease where abnormal (sickle shaped) hemoglobin are inherited. Causes fatigue, pooling if blood in spleen, low resistance to infection, and pain.
Autosomal recessive
Autosomal dominant
Two copies of abnormal gene must be present in order to develop le disease.
One copy of abnormal gene from one parent needed to get disease.
Two names of cells that become sperm and egg
Oogonial (overly)
Spermatogonial (testes)
Both diploid or 2n
Describe meiosis 1
Interphase- DNA duplicates 46 chromosomes (92) chromatids
Prophase- DNA condenses and homologous pairs match up for crossing over to transfer genetic information.
Metaphase- Chromosomes in pairs at equator of cell
Anaphase- Chromosomes pulled away
Telophase and cytokinesis- 2 new nuclei form 2 new cells
Describe meiosis 2
Prophase 2-Spindle form
Metaphase 2- Chromosomes lime up in single file line
Anaphase 2- Chromatids pulled away
Telophase 2 and cytokinesis- 4 haploid cells formed
What is the meaning of each….
P
F1
F2
P=parental generation
F1- First filial generation
F2- Second filial generation
Purebred
Hybrid
Organism that is the offspring of genetically similar parents that were both homozygous for a trait.
Organism that is the offspring of genetically dissimilar parents.
Dominant
Recessive
Expressed in phenotype
Only expressed in phenotype when paired with another recessive allele
Why do two heterozygous Tall plants create three tall and one short?
The paired genes separate and recombine. (Law of segregation)
TtxTt=TT, Tt,Tt,tt
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