BIOL 3301 - Exam 1 UH Zieba

Transmission Genetics (Mendelian Genetics)

Is the study of the transmission of traits in successive generations

Evolutionary Genetics

Studies the origins of and genetic relationships among organisms, and the evolution of genes and genomes

Molecular Genetics

Studies inheritance and variation of nucleic acids, proteins, and genomes

Genes

Are the physical units of heredity

Chromosomes

Are long molecules of double-stranded DNA and protein, which contains genes

Genome

The complete set of genes or genetic

Phenotype

The observable traits of an organism

Genotype

The genetic constitution of an organism

Alleles

Alternative (variant) forms of a gene

Diploid

Have two copies of each chromosome in their somatic cells

Haploid

Have one copy of each chrosomes in their germ cells

Evolution

The theory that all organisms are related by a common ancestry and have diversified over time

DNA

Strands are formed by nucleotides

Central Dogma of Biology

Describes the flow of hereditary information

Law of Segregation

Maternal
Paternal

Law of Independent Assortment

Different traits can segregate independently between generations

Locus

Place on a chromosome where the gene is located

Allele

A form of a gene that exists at a single locus

Reverse Genetics

Starts with the gene sequence and works backwards to the Mutant

The basis for segregation and independent assortment is in the process of

Meiosis

Mendel's Law of Segregation

-Each gamete get only one of two units of inheritance
-Progeny then gets one maternal and one paternal copy

Monohybrid Cross

A cross in which the two organisms crossed are both heterozygous for one gene

Punnett Square

Method of diagramming a genetic cross is a simple tool of genetic analysis

Mendel's Law of Independent Assortment

The inheritance of two or more traits simultaneously

9:3:3:1

-Illustrate Law of Independent Assortment
-Generated in dihybrid crosses

1:2:1

Heterozygotes are crossed

3:1

Concept of Dominance

Product Rule

-The probability that two events both occurring is the product of each event occurring separately
-2 or more events are independent of one another, and likelihood of happening simultaneously is product of individual probabilities

Sum Rule

-The probability that either of two mutually exclusive events will occur is the sum of the probability of each event
-Defines joint probability of occurrence of any 2 or more mutually exclusive events

Conditional probability

Involves questions asked after a cross has been made and is applied when information about the outcome modifies the probability calculation

Chi Square Value

Determines the probability that a difference is caused by chance

Sex-linked Inheritance

Refers to transmission of genes on sex chromosomes

X-linked Inheritance

Refers to the inheritance of genes on the X chromosome

Pedigree

Are a way of tracing the inheritance of traits in humans and some animals

Autosomal Dominant Inheritance

1. Each individual who has disease has at least 1 affected parent
2. Male & female are affected in equal number
3. Either gender can transmit disease allele
4. 1/2 offspring expresses disease if one parent is affected
5. 2 unaffected parent wont have children with disease
6. 2 affected parent may produce unaffected parent

Autosomal Recessive Inheritance

1. Individual who have the disease are often born to parents who do not
2. If one parent has disorder, risk child will have it depend on genotype of other parent
3. All parents-all off springs
4. Sex ratio of affected offspring is expected to be equal
5. Disease not seen in each generation, but if affected child is produced by unaffected parent, risk to subsequent children is 1/4
6. Disease is rare in population, unaffected parent of affected are more likely to be related to one another

Mitosis

-Produce 2 identical daughter cells that are identical exact genetic replicas of the parental cell
-Diploid number of chromosomes (2n) is maintained throughout cell cycle
-2n stays 2n

Meiosis

-Making gametes with n=1
-Produces gametes that have 1/2 the number of chromosomes as the original
-The basis for the independent distribution of traits
-Basic mechanism that leads to formation of gametes

Cell Cycle Checkpoints

Are monitored by protein interactions for readiness to progress to next stage

S Phase

Is followed by 2 division stages called Meiosis 1 & 2 with no DNA replication between them

Meiosis 1

1. Homologous chromosome pairing
2. Crossing over between homologous chromosomes
3. Segregation (separation) of homologous chromosomes, which reduces chromosomes to the haploid number

Independent Assortment

-Illustrated by behavior of 2 pairs of homologs during meiosis

Sex Determination

Involves the genetic and biological processes that produce the male and female characteristic of a species

Nondisjunction

Failed chromosome separation

Dosage compensation

Any mechanism that compensated for the difference in number of copies of genes between males and females

Haplosufficient

-The dominant wild-type allele
-Mean that one copy of it is enough for normal function in heterozygotes

Haploinsufficient

-The wild-type allele
-Mean that one copy of it is not enough for normal function

Loss-of-function mutation

There is a significant decrease or complete loss of functional gene product

Gain-of-function mutation

The gene product acquired a new function or expresses increased wild-type activity

Codominance

There is a detectable expression of both alleles in the heterozygotes

Penetrant

When the phenotype is consistent with the genotype

Fully penetrant

When genotype is always expressed in the phenotype

Incomplete penetrance

Traits that are nonpenetrant in some individuals

Epistasis

The effect of one gene is dependent on the presence of one or more 'modifier genes'

Mitochondria

-Generates ATP in eukaryotic cell
-Double membrane structure

Chloroplast

-Subset of organelles known as "plastids"
-Triple membrane
-Where photosynthesis happens in a plant cell

Replicative segregation

Random segregation of organelles during replication

Uniparental Inheritance

Organelles are usually inherited only from mother

Heteroplasmy

Multiple organelle genotypes in a single individual

Small genomes

Organelle genomes have few genes and descend from endosymbiotic bacteria

Mitosis result

Each daughter cell end up with 2 copies of each chromosome

Meiosis result

Each daughter cell end up with 1 copy of chromosome