Download An Introductory Overview of Cells, Chemical Bonds & Energy

Lecture no.3
An Introductory Overview of
Cells
1
22/05/2017
Lecture no.3
What We Will Be Covering-I?
 What is a Cell?
 The Two Types of Cells ?
 The Exception?
 The Organelles and Their Functions.
2
22/05/2017
Life begins with cells
Lecture no.3
 Cell came from Latin word mean small room.
 A cell is the functional and structural unit of all living
organism.
 The Cell Theory --1839 by the German botanist Matthias
Jakob Schleiden and German physiologist Theodore
Schwann.
3
22/05/2017
Cell Theory
Lecture no.3
 All living things are made up of cells.
 Cells are the smallest working units of all living things.
 All cells come from preexisting cells through cell division.
4
22/05/2017
Lecture no.3
Plant Stem
Amoeba
Proteus
Examples of Cells
Bacteria
Nerve Cell
5
22/05/2017
Red Blood
Cell
Types of Cells
Lecture no.3
1. Prokaryotic
• Bacteria
• Archaea
2.
Eukaryotic
 Unicellular
• Protists
 Multi-cellular
• Fungi
• Plants
• Animals
6
22/05/2017
Prokaryotic Cells
Lecture no.3
• Characteristics
 Unicellular (some multi-cellular).
 Lacks a membrane bound nucleus.
 Lacks membrane bound organelles.
 Has a cell membrane and cell wall.
 Has ribosomes (protein production).
 Circular DNA.
7
22/05/2017
Eukaryotes
Lecture no.3
• Characteristics
 Unicellular (Protists).
 Multicellular (fungi, plants, animals).
 Membrane bound Nucleus.
 Contains Organelles.
 Linear DNA.
8
Typical animal cell
Typical plant cell
22/05/2017
Types of Eukaryotic Cells
Lecture no.3
1. Somatic





Greek for “body’’
All cells in the body except the sex cells.
Found in the bones, skin, organs, tissues, blood.
Reproduce by Mitosis.
All somatic cells in a human body have the same genetic
information (except RBC)
2. Germ




9
The Sex Cells.
Sperm and Ova.
Reproduce by Meiosis.
Are haploid e.g. in humans: 23 chromosomes
22/05/2017
Lecture no.3
Is there any
exception ?
10
22/05/2017
The Exception: Viruses
Lecture no.3
• Characteristics
 Latin for “poison”.
 Does not meet all the criteria of “Life”
 Viruses are not cells; they are supramacromolecules made of two types of
macromolecules i.e. proteins and nucleic acids
 Outer coat is made of proteins and inner core
is nucleic acid, which may be either DNA or
RNA, but not usually both.
 Require a host to replicate.
11
22/05/2017
Lecture no.3
Cell Parts
Organelles
12
22/05/2017
I- Surrounding the Cell
Lecture no.3
- Cell Membrane
- Cell wall
Outer membrane of cell that controls
movement in and out of the cell.
Made of phospholipid bilayer with
embedded proteins (enzymes, receptors,
channels etc).
Place of communication with the
environment and other cells.
 13
“Gate of the Cell”.
Most commonly found in plant
cells & bacteria.
Made of mucopolysaccharides
(yeast, procaryotes) or cellulose
(plants)
“Supports & protects cells”.
22/05/2017
Lecture no.3
II- Inside the Cell
- Nucleus
First described by Robert Brown in
1831.
Largest organelle.
 Separated from cytoplasm by nuclear
membrane in eucaryotes.
 Contains genetic material – DNA.
 “Control Center”
14
- Nuclear membrane
 Double membrane envelop that
surrounds nucleus.
 Contains nuclear pores which is place
of selective transport between
cytoplasm and inside of nucleus
(proteins, mRNA)
 “Gate of the Nucleus”
22/05/2017
Lecture no.3
Continue…
- Chromosomes
In nucleus.
 Present in the form of strings of
DNA and histones.
Contain instructions for traits &
characteristics .
 “Director of the Cell”
15
- Nucleolus
 Inside nucleus.
 The nucleolus plays an indirect role
in protein synthesis by producing
ribosomes.
 Nucleolus is not a structure!!! Just a
visible region.
22/05/2017
Lecture no.3
Chromosomes in eukaryotes & prokaryotes are different
PROKARYOTES
EUKARYOTES
• single chromosome plus plasmids
many chromosomes
• circular chromosome
linear chromosomes
• made only of DNA
made of chromatin, a
nucleoprotein (DNA coiled around
histone proteins)
• found in cytoplasm
found in a nucleus
• copies its chromosome and
divides immediately afterwards
copies chromosomes, then the cell
grows, then goes through mitosis
to organise chromosomes in two
equal groups
© 2007 Paul Billiet ODWS
Numbers of chromosomes
Lecture no.3
• Constant for each cell in the body (except sex cells which only
have half sets).
• Constant throughout the life of an individual.
• Chrosomes are of two types: autosomes (same in males and
females) and sex (X and Y) chromosomes
• Constant for all members of a species.
Lecture no.3
Human Genome Basics
• Most human somatic cells are diploid, having 2 copies of
each chromosome, one from each parent.
• The gametes, sperm & egg, are haploid, with 1 copy of each
chromosome.
• Humans have a haploid number n of 23, meaning that
there are 23 chromosomes in a complete haploid set. Thus,
gametes have 23 chromosomes and diploid cells have 46.
The pairs of chromosome in a diploid cell are called
homologues.
• The X and Y chromosomes are sex chromosomes, and the
other 22 chromosomes are called autosomes.
• Normal males are XY and normal females are XX. Thus,
sperm cells either contain an X or a Y. Eggs always contain
an X chromosome.
Conti…
• In somatic cells: diploid (2n) cell: 23 x2= 46 chromosomes
: 22 pair of autosomes + XY chromosomes
: 22 pairs of autosomes + XX chromosomes
• In germ cells:
•
Sperms are of two types:
 22 autosomes + Y chromosome
 22 autosomes + X chromosome
•
19
Ova has: 22 autosomes + X chromosome
22/05/2017
Lecture no.3
Chromosomes and reproduction
20
22/05/2017
Lecture no.3
Continue…
- Cytoplasm
-Endoplasmic Reticulum
Gel-like material.
The portion of the cell enclosed by the cell
membrane but not part of any organelle
It stores the organelles, water, and the
chemicals in it.
 “Area of Movement”.
The transportation center for the cell.
Smooth and rough types.
SER Site of fatty acid and
phospholipid synthesis, While RER
place
of
extracellular
proteins
synthesis
21
22/05/2017
Lecture no.3
Continue…
- Ribosomes
Found in the cytoplasm and on the ER.
Their job is to make proteins.
The nucleus makes the ribosomes.
22
- Mitochondria
Place of oxidative metabolism and
ATP production.
Contains its own DNA and
ribosomes.
 “Powerhouse of the Cell”
22/05/2017
Lecture no.3
Continue…
- Golgi Bodies
Package and to move protein to the
out side of the cell.
They also process proteins from
ribosomes that are located on the ER.
23
- Lysosome
Digest the wastes and unwanted
organelles.
Acidic organelles - low pH due to proton
pump (pH=5) in the membrane.
Contain many degradative enzymes
such as acid hydrolases.
22/05/2017
Tay-Sachs disease :
is a genetic defect in one
of specific lysosomal
hydrolases
24
22/05/2017
Lecture no.3
Continue…
- Vacuoles
The vacuole in the plant cell is larger
than the vacuole in the animal cell.
Membrane-bound sacs for storage,
digestion, and waste removal.
 “Storage Tanks” .
25
- Chloroplast
Contains green chlorophyll.
 Where photosynthesis takes place.
 “Food Producers” .
22/05/2017
Summary
26
Lecture no.3
22/05/2017
Lecture no.3
See you later to
continue with the
The structure and
properties of
Nucleotides
27
22/05/2017