Genetics 9

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genetics

the branch of biology that studies heredity and variation in organisms

Heredity

the passing of characteristics from parents to offspring

Inheritance

it is the acquisition or reception of genetic quality's appearance to offspring. In sexual reproduction the genetic materials of two parents is combined and passed on to one individual.

Variation

Any difference between individuals of the same species. It is a state of having different traits and characteristics

Mandelian Genetics

It is one of the 3 branches of genetics. Also known as transmission genetics. It reviews the basic laws of inheritance that were described by Gregor Mendel.

Molecular genetics

One of the 3 brances of genetics. it deals with the chemical nature of the gene, the mechanisms of transmission, and its varied applications.

population genetics

One of the 3 branches of genetics. The behaivior of a particular gene on a group of organisms and how gene frequency is affected by environmental factors.

Genetic determines..

-Gender
-Physical Characteristics
-Potential diseases
-Intelligence
-Blood type
-Amnormalities

Application of genetics

-Animals and plants improvement
-Medicine
-Genetic counseling
-Legal application
-Genetic Engineering
-Genetic Test
-Improve crop yields
-Solve Agricultural problems

Gregor Johann Mendel

"Father of Genetics" An Augustinian monk discovered the basic principles of heredity through experiments in his monastery's garden. First scientist to give a satisfactory explanation of mechanisms of heredity.

Reason for using Pea (Pisum sativum)

Presence of observable traits with contrasting forms. Produces manu offspring in one cross. Short life cycle/short generation time. Ease in manipulating pollination. he crossed pollinated pea plants with opposite characteristics. tall with short, smooth with wrinkled, green seeds with yellow seeds etc.

Monohybrid Cross

A mating event between two parents that are heterozygous in respect to a single gene. This means that each parent carries two different alleles for the gene.

Phenotype

refers to the observable physical properties of an organism. This includes the organisim's appearance, development and behavior.

Genotype

An organism's complete set of heritable genes or genes that can be passed down from parents to offspring.

Allele

any alternative forms of genes in a genotype. It is represented by a letter

Dominant Trait

are inherited characteristics that appear in an offspring if it is contributed by a parent though dominant allele. it is represented by CAPITAL letter alleles

Recessive Traits

recessive traits are the weak, unexpressed trait of pair of alleles that has no effect in the phenotype of the heterozygous individual. It is represented by small letter alleles.

Homozygous traits

made up of two same alleles.

Heterozygous traits

made up of two different alleles

Punnett Square

Named from its inventor, Reginald Punnett.
It is a diagram made of boxes used to predict the expected results of a genetic cross by considering all the possible combinations of gametes in a cross.

Rule of Unit Factors in Pair

Genetic characters are controlled by unit factors in pairs.
In other words, genes are present in two associated copies in diploid organisms
Example: DD plants have two alleles for tallness, dd plants have two alleles for dwarfism.

Principles of Dominance and Recessiveness

In the case of unlike unit factors, one can be dominant and the other can be recessive.
In other words, when two different alleles of a gene are present, one may show its effect while the other may be masked.
Example: Dd plants have a tall allele D and a dwarf allele d, but are phenotypically tall

Law of Segregation

During the formation of gametes, unit factors segregate randomly.
❑In other words, when sperm and eggs are formed, one of each allelic pair is randomly distributed to each gamete.
Example: a Dd plant makes pollen or eggs, each randomly receives either the D allele or the d allele.

law of independent assortment

the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.

Chromosomes

It is where genetic material or the gene is located which in turn is found in the nucleus.
These are coiled DNA and associated with proteins called histones.

P arm

the label for the short arm of the chromosome

q arm

the label for the long arm of the chromosome

centromere

this is the chromosomes construction point, whoch divide the chromosomes into sister chromatids, or arms

sister chromatid

it is called that way because they consider reproduction as a female trait.

Metacentric

is a chromosome whose centromere is centrally located.

Submetacentric

a chromosome whose centromere is located near the middle.

Acrocentric

A chromosome where the centromere is not central and is instead located near the end of the chromosome

telocentric

is a chromosome whose centromere is located at one end. 

Spermatogenesis

sperm cell production. **the origin and development of the sperm cells within the male reproductive organs, the testes**.

❑Produces 2 types of spermatozoa or sperm cells

❑X- bearing and Y-bearing cells

❑ “*heterogametic”*

Oogenesis

egg cell production. **the process of formation of female gametes**.

❑ Produces only 1 type of ovum or egg cell

❑      - X-bearing cell

❑      - “*Homogametic”*

formation of gametes

Where the genetic history of an individual starts

Sex cells

will undergo meiosis to produce cells with a haploid (n) number of chromosomes.

Fertilization

sperm cell (n) and egg cell (n) unites to restore the number of chromosomes (n + n \= 2n).

Haploid

refers to the presence of a single set of chromosomes in an organisms cell.

Diploid

refers to the presence of two complete sets of chromosomes in an organism cell with each parent contributing a chromosomes to each cell.

Traits

Specific characteristics of an individuals.
Can be determined by genes, environmental factors, or by a combination of both.

Autosomes

A type of chromosome. controls the inheritance of all the characteristics

44 chromosomes (22 pairs)

Sex chromosome

A type of chromosome. It determines the sex of the individual

2 chromosomes (last pair)

Variation

Term used to describe the variation in the DNA sequence.

Traits controlled by a single gene

Eye color
Freckles
Attached earlobes
Ability to roll your tongue

Trait determined by multiple allese

ABO blood type groups
Physical structures

Polygenic trait

A characteristics, such as height or skin color that is influenced by two or more genes,
EXAMPLES: height, weight, hair

sex-linked or X-linked genes

The genes on the X chromosomes
These are inherited through the X chromosomes.

y linked or holandric genes

The genes on the Y chromosomes.
These are inherited through the Y chromosomes.

sex influence genes

Are autosomal genes whose expression is affected by the sex of the individual.
occurs when phenotypes are different between males and females with the same genotype.

Sex limited Genes

Are autosomal genes whose expression is manifested in one sex only because of the sex hormones.
These traits can only be expressed in one sex or the other the traits are not found on the X and Y chromosomes meaning they are generally autosomal.

pedigree

A chart that shows the family history.
It also illustrates how a trait is inherited over several generations in our family.

carrier

Individuals who are heterozygous for the inherited trait but do not express it.
They can pass the allele of the trait to their children.

genetically modified organisms (GMO)

GMO is a plant, animal, microorganism, or other organisms whose genetic makeup has been modified in a laboratory using genetic engineering or transgenic technology.

GMO in plants

To produce a GM plant, new DNA is transferred into plant cells. Usually, the cells are then grown in tissue culture where they develop into plants. The seeds produced by these plants will inherit the new DNA.

GM plant Benefits

-increased crop yields
-reduced need for pesticides
-reduced costs for food or drug production
-greater food security, and medical benefits
-enhanced nutrient composition and food quality

GMO's in animals

Genetic modification of an animal involves altering its genetic material by adding, changing, or removing certain DNA sequences in a way that does not occur naturally.
❑It aims to modify specific characteristics of an animal or introduce a new trait, such as disease resistance or enhanced growth.
example:
Toxic to insects but not harmful to mammals.
GM use - To kill insects on GM cotton crops
Golden orb Weaver
Gene is switched on in mammary glands of GM goats to mass-produce the silk fiber for artificial tendons and ligaments and for bullet-proof vests and parachutes.