UNIT ONECELL DIVISION (MITOSIS)

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CHROMOSOMES Chromosomes form when the chromatin network in the nucleus of

the cell, coil up, shortens and thickens.

Each organism has a specific amount of chromosomes.

All humans have 46 chromosomes.

These chromosomes are arranged in identical pairs called homologous chromosome pairs –

Therefore humans have 23 homologous pairs of chromosomes.

These chromosomes is only visible during cell division processes.  

One chromosome consist of 2 chromatids and one centromere that attach the chromatids together.

Each chromatid consist of genes which in turn consist of DNA.

CHROMOSOMESTRUCTURE

X and Y chromosomes: gonosomes/sex-chromosomes

Colored bands represents different genes

THE PHASES OF THE CELL CYCLE

The cell cycle includes the following phases:

Interphase (include G1- , S- [DNA synthesis] and G2 phase)

Prophase

Metaphase

Anaphase

Telophase

The result is 2 identical cells.

Why is Mitosis important?

Allow an organism to grow.

Repairs damaged cells/tissue.

Replace dead cells/tissue.

Reproduction in some simple organisms.

Where does Mitosis take place?

In all somatic cells (include all body cells and excludes the sex cells – sperm/egg cells)

The process of Mitosis.

CONSIST OF A FEW PHASES:

INTERPHASE

PROPHASE

METAPHASE

ANAPHASE

TELOPHASE

INTERPHASE

Cell builds up enough energy for division process.

DNA replication occurs

Cell look normal, like before division

PROPHASE

Nuclear envelope and nucleolus disappear.

Chromatin become more tightly coiled, and condenses into individual chromosomes. Chromosomes arrange randomly in the cell.

Centrioli move to opposite poles, with spindle fibers stretching between them.

METAPHASE

The centrioli reached the opposite poles with the spindle fibers in between.

The chromosomes arrange randomly on the equator, each single chromosome attaching to a separate spindle fiber by means of the centromere.

ANAPHASE

The spindle fibers pull tight.

The centromers attaching the chromatids of the chromosomes split in half.

Daughter chromosomes move to opposite poles.

EARLY TELOPHASE – KARYOKINESIS (DIVISION OF NUCLEUS

Daughter chromosomes reach poles.

Nuclear envelope surrounds chromosomes.

Nucleolus reappear at each pole.

Chromosomes become less condense forming chromatin.

Two identical nuclei has been formed

LATE TELOPHASE – CYTOKINESIS (DIVISION OF THE CYTOPLASM)

Invagination of the cytoplasm and plasma membrane occurs. (Cleavage furrow forms in animal cells and a cytoplasmic plate forms in plant cells)

Continues until the cell in divided into 2 separate cells. (Identical to one another and to the original cell)

MITOSIS PROCESS

UNIT TWOPHOTOSYNTHE

SIS

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Photosynthesis

A process that converts carbon dioxide into organic compounds

In other words:

The chemical process by which plants capture sunlight and use it to convert carbon dioxide and

water into food.

What uses photosynthesis??

Green plants

Flowers

Trees

Some algea

A few various forms of bacteria

**Mostly flowers and trees**

Most essential components of photosynthesis:

These include:

Direct sunlight

Water

Carbon dioxide

Chlorophyll

Who benefits from photosynthesis?

The plants/algea/bacteria

Other living beings such as animals

Even humans!!

Parts of Photosynth

esis

StomatesMicroscopic hole in the

stem and leaves of plants

This is where carbon dioxide enters the plant

At the same time,

water is entering the

plant through the

roots.

After being absorbed by the roots:The water travels all the way through the

stem to reach the leaves.

Chlorophyll

Contained in the plant

This is what makes the green color

What does chlorophyll do besides make the plant green??

When sunlight falls on the plant, the

chlorophyll captures the energy in it, and stores it for further

use.

This energy is

eventually used to

convert water into

hydrogen and

oxygen.

This is combined with the carbon dioxide to produce the

food for the plant

Hydrogen

The oxygen is let out through the stomates

OXYGEN

*Hydrogen is used to produce

food*Oxygen is let out as waste

product

Photosynthesis is

important in the

respiration of

humans and animalsWe use the oxygen produced by this

to fulfill our oxygen intake to live.

Proteins

Fats

Water soluble sugars

Photosynthesis also produces:

WE DEPEND ON PLANTS (OR ANIMALS

THAT FEED ON PLANTS) TO GET

THESE BECAUSE OUR BODIES CANNOT PRODUCE THESE

NUTRIENTS ON THEIR OWN

Photosynthesis plays a vital role in regulating the life

cycle on earth!

Sunlight, water, and the plants work together to supply the raw source of energy to us and help us breathe in oxygen to live

on.

Life without photosynthesis

would be impossible!!!

UNIT THREE

HUMAN EVOLUTION

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What is Evolution?

It is the gradual change from one form to another through a period of time.

Lamarck’s Theory

Acquired traits can be inherited

He proposed that:

Organisms change as their environment changes

Darwin’s Theory

Charles Darwin

Darwin’s Theory

Published “Origin of Species”

Traveled around the world in the Beagle

He proposed that:

Organisms produce more offsprings than the available resources can support

Organisms fight for limited resources like food, territory, and other necessities of life. Only those who survive can produce their own offspring

Variation exists within species. For example, some gorillas have longer arms than others.

Natural Selection - The environment selects organisms with beneficial traits.

Adaptation

Adaptation

Lamarck vs Darwin

Jean Baptist de Lamarck

Charles Darwin

1809 1859

French Naturalist English Naturalist

Acquired traits can be inherited by an organism

Organism adapts to changes in the environment. Only the fittest organisms survive through natural selection.

EVOLUTION

NATURAL SELECTION

ADAPTATION

Gradual change from one form to another through a period of

timeThe environment selects organisms with

beneficial traits

A form modified to fit a changed environment

Evidences of Evolution

Any preserved part or tissue of an organism that once lived.

FOSSIL

Types of Fossils

Casts

The mold is filled with another material

Molds

Hard body structures

Imprints

Feathers and leaves that

form impressions on

rocks

Petrified Fossils

When minerals replace the

hard parts of organisms

Biochemical Evidences

Indicate that some organisms have similar DNA sequences, which suggest common ancestry

DNA

VARIATION

Patterns of Evolution

Divergent

Related organisms

become very different

Convergent

Distantly related organisms

develop similar characteristics

Convergent Evolution

REFERENCES

Shyla Turner *** Instructional Technology TR 9:30-10:45***

Isabel V. Neri

Ziningi Mthembu (student at university of Johannesburg)