Cell division
& Mendelian Genetics & Genetic
Inheritance &Molecular genetics

Cell division

Chromosome

Prokaryotic cell

Circular chromosome

Not associated with proteins

Eukaryotic cell

Prokaryotes

Binary fission

Eukaryotes

Mitotic cell division

Interphase

~90% of the cell cycle

- Can be divided into 3 phases

The cell grows during all three phases

Chromosomes are duplicated only during the S phase.

Mitosis and cytokinesis

Mitosis

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis occurs during telophase

In animal cells, cytokinesis occurs
by a process known as cleavage,
forming a cleavage furrow

In plant cells, a cell plate
forms during cytokinesis

Cells that can undergo mitotic cell division include

Epithelial cells, Bone marrow of animal tissues

Shoot and root apical meristems of plant tissue

Meiotic cell division

Objectives

. Sexual life cycle

To produce reproductive cells

Stage of Meiosis

prophase I

chromosome pairs with its homolog (synapsis) and crossing over occurs

metaphase I

pairs of homologs line up at the metaphase plate, with one chromosome facing each pole.

anaphase I

One chromosome of each pair moves toward opposite poles, guided by the spindle apparatus.

telophase I

Meiosis II

is very similar to mitosis

metaphase II

the sister chromatids are arranged at the metaphase plate

anaphase II

the sister chromatids separate.

telophase II,

the chromosomes arrive at opposite poles

Subtopic

Chromosomes

Human

23 pairs of chromosomes

46 per cell

Bacterial Chromosome

Double-stranded DNA

single circular chromosome

located in the cytoplasm

not bound with proteins

smaller circular DNA molecules

pick up new plasmids or lose them

Plasmids help bacteria to survive stress

RNA

Ribonucleotides

Uracil

Ribose

There are three kinds of RNA

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA

Genetics

Gregor Johann Mendel

Experimented with pea plantsfor 8 year

F 1 progeny resembles one of the parents

In F 2, the missing trait reappears in ¼ of the progeny

The ratio of two classes of progeny was 3 : 1

Mendel’s Principles

genes become separated in gamete formation

Members of one gene pair segregate independently from other gene pairs during gamete formation

test-cross

To test the equal gamete formation in F1

Dominant phenotype couldbe either homozygous
dominant or heterozygous

breeding the mystery individual with a
homozygous recessive individual

Mendel’s Law of Segregation

Two alleles of the same gene segregate equally

Different pairs of alleles assort independently

Probability and Genetics

Rule of multiplication

Chance that 2 or more independent events will occur
together

– probability of Pp x Pp -> pp

Rule of addition

Chance that an event can occur 2 or more
different ways

– sum of the separate probabilities

– probability of Bb x Bb -> Bb

Non-mendelian inheritance

Incomplete dominance

Codominance

Pedigree Analysis

Family tree

interrelationships of parents and children across generations

Inheritance patterns

Linked Genes

Sex Chromosomes

X-Y system

X-O system

Z-W system

Haplo-diploid system

DNA

the complex chemical

dictates life in two manners

transfers hereditary information
from generation to generation

controls the production of proteins

Chargaff’s rules

The base composition of DNA varies between
species

A=T, C=G

double helix

Antiparallel strands

• Right-handed fashion

DeoxyriboNucleic Acid