Heredity is the passing on of characteristics from one generation to the next. It is the reason why offspring look like their parents. It also explains why cats always give birth to kittens and never puppies. The process of heredity occurs among all living things including animals, plants, bacteria, protists and fungi. The study of heredity is called genetics and scientists that study heredity are called geneticists.
Through heredity, living things inherit traits from their parents. Traits are physical characteristics. You resemble your parents because you inherited your hair and skin color, nose shape, height, and other traits from them.
Cells are the basic unit of structure and function of all living things. Tiny biochemical structures inside each cell called genes carry traits from one generation to the next. Genes are made of a chemical called DNA (deoxyribonucleic acid). Genes are strung together to form long chains of DNA in structures known as chromosomes. Genes are like blueprints for building a house, except that they carry the plans for building cells, tissues, organs, and bodies. They have the instructions for making the thousands of chemical building blocks in the body. These building blocks are called proteins. Proteins are made of smaller units called amino acids. Differences in genes cause the building of different amino acids and proteins. These differences cause individuals to have different traits such as hair color or blood types.
A gene gives only the potential for the development of a trait. How this potential is achieved depends partly on the interaction of the gene with other genes. But it also depends partly on the environment. For example, a person may have a genetic tendency toward being overweight. But the person's actual weight will depend on such environmental factors as how what kinds of food the person eats and how much exercise that person does.
7. Genes are segments of strands of deoxyribonucleic acid (DNA).
DNA forms a double spiral (HELIX) that looks like a twisting ladder.
Each “rung” on the ladder consist of 4 basic chemicals that are placed in pairs of
either: Adenine and Thymine or Cytosine and Guanine
The sequence of the rungs are the individual genetic code that cause the
developing organism to grow arms, wings, skin, or scales.
8. There are TWO types of cell division
Mitosis and Meiosis
20. Turner Syndrome (X)
1 girl in 2,500 has
syndrome.
Female is shorter than
average and infertile.
Cognitive deficits
problems with visual-
spatial skills,
mathematics and
nonverbal memory.
21. (XYY) Syndrome
Rare abnormality in
men.
Occurs in 1 in 1,000
males.
Active in sex and sport,
learning difficulties,
delayed speech and
difficult time with
communicating.
22. Klinefelter Syndrome
(XXY)
1 male in 500 has
syndrome
Produces less
testosterone
Usually have enlarged
breasts
Mild retarded particularly
language, Infertile
23. Triple X Syndrome
(XXX)
1 girl in 1,000 has
syndrome.
Normal in appearance
Lower than average
language skills, poor
memory for recent
events
Development of external
sex organ normal
24. Genetic Abnormalities
• A number of disorders attributed to genes:
– Phenylketonuria (PKU)
– Huntington’s Disease
– Sickle-Cell Anemia
– Tay-Sachs Disease
– Cystic Fibrosis
– Sex-Linked Genetic Abnormalities
– Blood Linked Genetic Abnormalities
26. Cannot metabolize an
amino acid called
phenylalanine;
Builds up in body and
impairs functioning of the
central nervous system
(CNS);
Results are mental
retardation, psychological
disorders, physical
problems
27. No cure, but PKU can be detected in new born children through blood or urine
analysis; if identified placed on diets low in phenylalanine within three weeks of
birth and develop normally
29. Sickle-Cell Anemia
Common among African
American
Red blood cells take a
shape of sickle
obstructing blood and
oxygen supply
Impair cognitive and
academic functions,
organs failure
30.
31. Cystic Fibrosis
Caused by recessive
gene
Fatal hereditary
disease among
European Americans
30,000 Americans
have disorder, 10
million more are
carriers (1 in 31
people)