Bio 101

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Define genetics
Is the science that deals with Heredity, or natural Inheritance.
Who is the father of genetics?
Gregor Mendel was considered as the father of genetics because he was the first one to understand how DNA worked.
Know the importance of the science of genetics.
-helps us to understand how and why offsprings have a combination of their parents' traits.
- It has improved food production
- It has potential for solving problems related to inheritable human diseases
- It has help to control population growth
Know the blending theory of inheritance.
States that parents of constracting appearance produce offsprings with intermediate appearance.
Who developed the concept of generation mapping?
Mendel with pea experiment, formulated four fundamental laws of heredity.
What is Fillial?
-having the relation of a child to a parent.
-pertaining to the sequence of generations following the parental generation, each generation being designated by an F followed by a subscript number indicating its place in the sequence. F1
An alternative form of genes that are always at exactly the same position on homologous chromosomes is called:
Allele
What is a dominant allele?
is the expressed alleles, identified by capital letter
What is a recessive allele?
is the alleles that is not expressed, identified by small letter.
In genetic notation, what identifies the dominant allele?
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homozygous
organism that has two identical alleles for a particular trait. Eg. TT or tt
Heterozygous
organism that was two different alleles at a gene locus eg. Tt
Genotype
refers to alleles an individual receives at fertilization, genetic information controlling the phenotype
Phenotype
is the physical appearance of the individual
Monohybrid testcross
is used to determine if an individual with the dominant phenotype is homozygously dominant or heterozygously for a particular trait.
Dihybrid cross
observed phenotypes among F2 plants. Formulated law of independent assortment.
Define: testcross
Two-trait
is used to determine if an individual is homozygous dominant or heterozygous for either of the two traits.
simple dominance
the dominant allele codes for production of a protein and the recessive allele does not code for an effective protein.
Codominance
both alleles are fully expressed. Example an individual with blood type AB, both alleles produce an effective product.
incomplete dominance
exhibited when the heterozygote has an intermediate phenotype between that of either homozygote.
pleiotrop
A gene that affects more than one characteristic of an individual. Sickle cell(incomplete dominance)
epistasis
A gene at one locus interferes with the expression of a gene at a different locus. Human skin color(polygenic inheritance)
multiple alleles
when a trait is controlled by multiple alleles, the gene exists in several allelic forms. ABO blood types, results in more than two possible phenotypes for a particular trait.
polygenic inheritance
occurs when a trait is governed by two or more sets of alleles. Each dominant allele has a quantitative effect on the phenotype, and these effects are additive. Results in continuous variation of phenotypes
What causes Down Syndrome
Down syndrome occurs because of an abnormality characterized by an extra copy of genetic material on all or part of the 21st chromosome. Every cell in the body contains genes that are grouped along chromosomes in the cell's nucleus or center. There are normally 46 chromosomes in each cell, 23 inherited from your mother and 23 from your father. When some or all of a person's cells have an extra full or partial copy of chromosome 21, the result is Down syndrome.

The most common form of Down syndrome is known as Trisomy 21, a condition where individuals have 47 chromosomes in each cell instead of 46. This is caused by an error in cell division called nondisjunction, which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception. Trisomy 21 accounts for 95% of Down syndrome cases, with 88% originating from nondisjunction of the mother's egg cell.
autosomes
all but one pair of chromosomes in males and females are the same. Nonsex chromosomes, they do not determine sex.
sex chromosomes
determines sex of the individual, human female sex chromosome are XX, human male sex chromosomes are XY. Male sex chromosomes produce two different types of Gametes.
x-link genes
are genes carried on the X chromosome. Y chromosome does not carry these gene
linkages group
is a group of genes located on one chromosome that tend to stay together and separate only when crossing over occurs.
What is mutation
-permanent changes in genes or chromosomes that can be passed to offsprings if they occur in cells that become gametes.
-increases genetic variation among offsprings
-chromosomal mutations
-changes in chromosome number
when does monosomy mutations occur? What causes monosomy mutation
Monosomy mutation: occurs when an individual has only one of a particular type of chromosome. (2n-1), caused by non-disjunction during meiosis,
what causes nondisjunction?
nondisjunction occurs when homologous pair of chromosomes fail to separate during meiosis II. Nondisjunction occurs when sister chromatids fail to separate during meiosis II
inversion
segement of chromosome turns 180 degree
Translocation
movement of the chromosome to another, nonhomologous chromosome.
Deletion
occurs when an end of a chromosome breaks off
Duplication
is the doubling of chromosome segement
LAW OF UNIT CHARACTER
States that factors which always occur in pairs, control the inheritance of various traits.
Modern View: Alleles- Alternate form of genes that are always at exactly the same position on Homologous Chromosomes.
LAW OF DOMINANCE
States that in any given pair of factors(alleles) one may suppress or mask the effect of the other.
LAW OF SEGREGATION
-Each individual has two factors(alleles) for each trait
-The factors segregate during gamete formation (meiosis).
-Each gamete contains only one factor(allele) from each pair of factors(alleles)
-Fertilization gives each new individual two factors for each trait.
LAW OF INDEPENDENT ASSORTMENT
-each pair of factors segregates independently of the other pairs.
-all possible combinations of factors can occur in the gametes.
Gene locus
The particular location on the Homologous pair of Chromosome where the alleles are present
when does trisomy mutations occur? What causes trisomy mutation
occurs when an individual has three particular type of chromosome(2n+1). Caused by nondisjunction during meiosis.
Particulate Theory of Inheritance
States inheritance involves reshuffling of the same genes from generation to generation
Phenotypic ratio of Monohybird
3 tall 1 short
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