Introduction of Genetics

The Nature of Heredity

The study of heredity and the variation of inherited characteristics

HEREDITY: the passing of traits from parents to offspring

GENETICS

Genetic information is contained in a molecule of DNA

The modern DNA model has 3 parts:1. Composed of pentose sugar, a

phosphate group and one of four nitrogenous bases (Levene, 1920)

2. The proportion of nitrogenous bases are equal. (Chargaff, 1940)

3. DNA has a helix shape (Franklin, 1951)

DNA

The backbone of DNA is composed of phosphate group and pentose sugar.

The nitrogenous bases pair up:◦Thymine-Adenine◦Cytosine-Guanine

DNA

COMPLEMENTARY BASE PAIRING: pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand

You only need to know the nucleotide sequence for one strand

DNA

GENE: a segment of a DNA molecule that codes for a particular trait Found at a specific location on a chromosome

LOCUS: the location of a gene on a chromosome

CHROMOSOME: carries information for hundreds or thousands of different genes

GENETIC MATERIAL

REPRODUCTION

ASEXUAL SEXUAL

The production of offspring from a single parent

The genetic makeup of the offspring is identical to that of the parent

The production of offspring from the fusion of two sex cells

The genetic makeup of the offspring is different from that of either parent

There are 3 stages to the cell cycle:◦INTERPHSE◦MITOSIS◦CYTOKINESIS

CELL CYCLE

The period between cell divisions, where the cell grows, DNA replicates and the cell prepares for mitosis.

INTERPHASE

There are three parts to interphase:

◦G1 (First Gap) Phase: the cell is growing and preparing for replication

◦S (Synthesis) Phase: duplication of genetic material

◦G2 (Second Gap) Phase: cell begins final prep for cell division

INTERPHASE

The chromosomes in the nucleus form a mass of thread like structures called CHROMATIN

The replication of chromosomes results in a pair of SISTER CHROMATIDS

INTERPHASE

The process by which a cell divides the genetic material in its nucleus into two identical nuclei

Used for: Growth Reproduction Repair

MITOSIS

There are four phases of mitosis: PROPHASE METAPHASE ANAPHASE TELOPHASE

PHASES OF MITOSIS

Chromosomes shorten and thicken

Centrioles move to opposite poles of the cell

Spindle fibres form Nuclear membrane starts to dissolve

PROPHASE

Spindle fibres move to align the chromosomes

Chromosomes are lined up at the equator of the cell

METAPHASE

The chromosomes move to opposite poles of the cell

The chromosomes are pulled by their centromeres

ANAPHASE

Chromosomes are at opposite poles and start to unwind

Spindle fibres start to dissolve

Nuclear membranes reform

TELOPHASE

The process in which a cell divides its cytoplasm in to two new INDENTICAL daughter cells

The same number and type of chromosomes in each cell

CYTOKINESIS

The process of producing one individual that is genetically identical to another using a single cell or tissue

EXAMPLES: “Dolly” the sheep Genetically Modified Organisms Pharmaceutical products

CLONING

Cancer is occurs when cells divide uncontrollably

There are two kinds of cancer tumors: BENIGN: the cancer cells are not capable of spreading

MALIGNANT: the cancer cells are capable of spreading

CANCER