The study of genes and the inheritance of traits

Gregor Mendel’s work determined that hereditary characters are transmitted to offspring by separate units

Later known to be genes

These are features you exhibit physically

( your looks)

Example: Eye color -green

The different versions of a characteristic

Example: blue, green, and brown eyes

Occurs when traits are passed down from parent to child.

Most human cells contain 46 chromosomes:

2 sex chromosomes (X,Y):XY – in males.XX – in females.

22 pairs of chromosomes named autosomes.

6

1

DNA stands for deoxyribose nucleic acid

This chemical substance is present in the nucleusof all cells in all living organisms

DNA controls all the chemical changes which take place in cells

The kind of cell which is formed, (muscle, blood,nerve etc) is controlled by DNA

The kind of organism which is produced (buttercup,giraffe, herring, human etc) is controlled by DNA

2

DNA is a very large molecule made up of a long chain of sub-units

The sub-units are called nucleotides

Each nucleotide is made up of

a sugar called deoxyribose

a phosphate group -PO4 and

an organic base

3

Ribose is a sugar, like glucose, but with only fivecarbon atoms in its molecule

Deoxyribose is almost the same but lacks one oxygen atom

Both molecules may be represented by the symbol

4

The most common organic bases are

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

5

The deoxyribose, the phosphate and one of the bases

adenine

deoxyribose

PO4

Combine to form a nucleotide

6

A molecule of DNA is formed by millions of nucleotides joined together in a long chain

PO4

PO4

PO4

PO4

sugar-phosphate backbone

+ bases

7

In fact, the DNA usually consists of a double strand of nucleotides

The sugar-phosphate chains are on the outsideand the strands are held together by chemical bonds between the bases

8

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

9

NitrogenousBase (A,T,G or C)

“Rungs of ladder”

“Legs of ladder”

Phosphate &Sugar Backbone

Bits of information passed down from parent to child.

Made of chemicals called DNA.

How DNA works

National Human Genome Research Institute - NIH

The sequence of bases in a gene is a code instructing the cell how to construct a particular protein – i.e. the number of amino acids and the order in which they are to be assembled.

His

Met Phe

His

Glu

Pro

Cys

Cys

M A Glu K

Recombinant DNA technology

PCR

Botting technique

Southern Blotting

Western Blotting

Northern Blotting

Synthesis of hormones

Laboratory diagnosis

Gene therapy

Use in forensic medicine

Trisomy 21

Turners syndrome

Klinefelters syndrome

X-linked disorders

Point mutation

Frame shift mutation

Oncogenes (RET proto-oncogene)

Tumor suppressor genes ( p53 , RB gene)

Telomerase

Apoptosis is also called as programmed cell death

Controlled by cell’s genes

Cell suicide

Different from necrosis

No inflammation

Physiological process

Apoptosis for proper development of tissues

Apoptosis for normal functioning of body

Apoptosis of cells that are a threat to integrity of tissues

Internal stimuli

External stimuli

Final common pathway

DNA fragmentation

Cytoplasm and chromatic condensation

Membranous bleb formation

Phagocytosis of debris