intermediate biology 6

Scripture for this P.A.C.E

“And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying, Abba, Father.”

-Galatians 4:6

Recombinant DNA

DNA made from connecting fragments of DNA that are ontained from different sources

Genetic engineering

The field of biotechnology that is used to alter the genome of a living cell for medical, industrial, and agricultural purposes

Biotechnology

The identification and use of living organisms and their systems to make products that are useful to man

Cloning

The creation of some type of living matter such as a cell or organism from an existing cell or organism with identical genetic make-up as the original

Stem cell

Found in the embryo stage and can still differeniate

chromosomal DNA

DNA found in the chromosomes

nuDNA/nuclear DNA

DNA found in the cell nuclues and contains the genetic material from both parents

Genetics

The study of heredity ( study of inherited characteristics) and genetic variation

Segregation

The separation of the two alleles of each gene during meiosis into separate sex cells

Sickle cell anaemia

This is a disorder that affects the red blood corpuscles or cells ( RBCs). Normal RBCs are round and flexible in order to travel freely through narrow blood vessels. They also contain many haemoglobin molecules to transport oxygen to all parts of the body. People suffering with sickle cell anaemia have a mutation in a gene on chromosome 11 which leads to abnormal formation of haemoglobin molecules. This results in RBCs becoming rigid and having a concave shape very much like that of a sickle used to cut wheat. These irregularly shaped cells are not able to transport oxygen efficiently, and they tend to get stuck in the blood vessels causing pain, strokes, delayed growth, and jaundice. Sickle cell anemia is inherited in an autosomal recessive pattern which means that it only shows up in the recessive condition. Thus, both parents could be carriers displaying no symptoms of the disease, but could produce a child with the disease.

Incomplete dominance

No one gene is dominant over the other and both genes have equal influence in expressing the phenotype

Autosomes

Chromosomes that are not sex chromosomes; they are found in the body's cells and not in the sex cells (gametes)

Hybrid

An offspring of two genetically different parents

Heterozygous

An individual having two contrasting genes in the corresponding positions of homologous chromosomes.

Monohybrid cross

Cross involving only one characteristics at a time

Punnet square

A diagram (of squares) that is used to predict an outcome of a particular cross or breeding experiment

Pedigree diagram

A table or chart showing the line of ancestors of an individual animal or person

Karyotype

A visual representation in which a cell's chromosome are arranged according to size and classification

Mutation

Change in the structure of a gene or chromosome

Gene

A segment of a chromosome (DNA) containing a unit of genetic information. Two genes are responsible for each characteristic of an individual.

Gamete

A reproductive cell or sex cell ( sperm or ovum)

Dihybrid cross

A cross involving two characteristics at a time

Monohybrid

A cross involving one characteristic at a time

Homozygous

An individual having two of the same genes ( BB, rr) for a particular characteristic so that both the alleles are expressed in the phenotype. A homozygous individual is referred to as pure-bredding for that characteristic.

Filial generation

The first generation after mating, namely F1; and after further mating F2

Phenotype

The physical (external) appearance of an individual as determined by the genetic make-up of the individual

Genotype

The genetic make-up of an individual as reflected in the chromosomes

Locus

Position of a gene on a chromosome

Dominant gene

A gene that express itself in the phenotype of an individual and masks the effects of the recessive gene

Allele

Alternative form of a gene found on the corresponding positions on homologous chromosomes

Mendel's First Law: Law of Segregation

Each characteristic is controlled by two genes situated on homologous chromosomes. When gametes form during meiosis, the two genes are separated or segregated enabling a gamete to contain one of the two alleles from each parent.

Mendel's Second Law: Law of Independent Assortment

The various genes are separate entities and do not influence each other in any way. They sort themselves out independently during gamete formation, since homologous chromosomes arrange themselves randomly along the equator of the cell during metaphase I.

Haemophilia

Haemophilia is a sex-linked characteric, found on the X-chromosome and its gene is represented by an “h” written next to the X-chromosome (Xh). It is caused by a recessive gene on the X-chromosome and is usually passed down from mother to son. It is very rare in females, since it is a recessive trait and will only show up phenotypically if both the recessive genes are present. However, in males, there is only one X-chromosome and it seems that the presence of this defective gene (even though there is only one allele) results in this disorder. The blood of the people suffering with haemophilia does not clot properly since they do not produce certain blood clotting factors.

mtDNA/Mitochondrial DNA

1. DNA that is found in the mitochondria

2. Mitochondria inherited from the maternal line only

Gene Mutation

A gene is a short length of a DNA molecule. Sometimes, during DNA replication, the base pairs are altered and the new DNA is slightly different from the original, or it might be the addition or subtraction of an entire chromosome or even an entire set of chromosomes. Thus, one or more genes become altered or mutated. Gene mutations may be caused by X-rays, ultraviolet radiation, and certain chemical agents. These mutations are genetic disorders that cause diseases that are a result of abnormalities in the individual l's DNA. Each abnormality (genetic disorder) can be classified into one of three levels: single-gene disorders, chromosome abnormalities, and multifactorial diseases.

Colour Blindness

Colour blindness is the reduced ability for humans to distinguish between certain colours. Vision is not affected, only the ability to distinguish between certain colurs. Colour blindness is a sex-linked inherited disease passed on from parents to their children through a faulty vision colour gene on the X-chromosome. It is a recessive. It is very rare in females because a female with with this recessive trait does not feel the effects since her other X-chromosome is dominant and cancels out the colour blindness. Colour blindness with only shoe up phenotypically if both the recessive genes are present. Even she may display no symptoms of it, she can still be carrier for the disease.