INTRODUCTION TO GENETICS A.

NARROW DEFINITION – STORAGE,

EXPRESSION AND REPLICATION OF GENETIC
1665- ROBERT HOOKE INFORMATION AND ITS MOLECULAR DETAILS
•IMPROVED EXISTING COMPOUND - ‘MOLECULAR GENETICS’
MICROSCOPE B. BROAD DEFINITION – VERY GENERAL; ANY
• OBSERVED A PIEC OF CORK KIND OF RESEARCH ON THE STRUCTURE AND
• COINED THE TERM CELL FUNCTION OF BIOLOGICAL MACROMOLECULES
• WROTE THE BOOK - ‘MOLECULAR BIOLOGY’
MICROGRAPHIA
2 MAIN FACTORS THAT ATTRIBUTED TO THE
1683- ANTONIE VAN LEEUWENHOEK RAPID DEVELOPMENT OF MOLECULAR
• MASTER MICROSCOPE MAKER BIOLOGY
• PERFECTED SIMPLE MICROSCOPE • INCREASED RESOLVING POWER PROVIDED BY
• DISCOVERED BACTERIA AND PROTOZOA, ELECTRON MICROSCOPY AND X-RAY
CALLED THEM ‘ANIMALCULES’ DIFFRACTION
• THE CONVERGENCE OF FIELD WITH OTHER
1833- ROBERT BROWN BRANCHES OF BIOLOGICAL RESEARCH,
• DISCOVERED NUCLEUS ESPECIALLY GENETICS, PHYSIOLOGY, AND
• BROWNIAN MOVEMENT BIOCHEMISTRY

1839- THEODORE SCHWANN GREGOR MENDEL (1865)– FATHER OF

 ANIMAL CELLS GENETICS
 CELL THEORY - AUSTRIAN MONK WHO DISCOVERED THE
PRINCIPLES OF HEREDITY THROUGH
1840- ALBERT VON KOLLIKER EXPERIMENTS IN HIS GARDEN
•DISCOVERED THAT SPERM AND EGGS ARE • CORRENS, TSCHERMACK, AND DE VRIES
ALSO CELLS (1901) – BOTANISTS
- INDEPENDENTLY REDISCOVERED MENDEL’S
1845- ALEXANDER CARL HEINRICH BRAUN LAWS
REWORKS THE CELL THEORY, CALLING CELLS • MORGAN AND COWORKERS – ESTABLISHED
THE BASIC UNIT OF LIFE CHROMOSOME THEORY OF HEREDITY

1855- RUDOLF VIRCHOW Cell Structures and Organelles

• STATED THAT CELLS ARE GENERATED BY
EXISTING CELLS CELL ORGANELLE
• A cell organelle is a tiny cellular structure that
WALTER SUTTON AND THEODOR BOVERI performs specific functions within a cell
• RESPONSIBLE FOR IDENTIFYING THE • which divide the cell into many small
CHROMOSOME AS THE HUB FOR HEREDITY compartments for different biochemical
reactions.
JAMES WATSON AND FRANCIS CRICK
• STUDIED THE STRUCTURE OF DNA THREE TYPES OFCELL ORGANELLES
• DOUBLE HELIX  General cell
 Temporal cell
DEVELOPMENT OF MOLECULAR BIOLOGY  Cell type specific cell organelle
• ROBERT OLBY (1990)
  biogenesis.
GENERAL CELL
 Cell Membrane  Mithocondria
 a biological membrane that separates the
interior of the cell from the outside space  Mitochondrion performs cellular
and protects the cell from its environment. respiration, which converts glucose and
 Cytoplasm oxygen to adenosine triphosphate (ATP).
 Cytoplasm refers to all material within a cell, ATP is the biochemical energy “currency” of
enclosed by the cell membrane, except for the cell for all activities.
the cell nucleus.  Mitochondria (in plant cells, chloroplasts,
 Cytoplasm includes the cytosol and all the too) are the only organelles that have their
organelles. own DNA other than the nucleus.
Mitochondrial DNA (mtDNA) is circular and
 Cytosol encoded only 13 genes.
 is the cellular fluid inside the cell. It fills up
the entire intracellular space.  Peroxisome
 Water is the most abundant molecule inside  Peroxisome is a spherical organelle
the cells, accounting for 70% or more of responsible for the fatty acid (oil molecule)
total cell mass. breakdown to generate energy.
 Peroxisomes in the liver cells also handle
 Cytoskeleton the detoxification of many chemicals,
 is the cells’ skeleton system. Its network including alcohol and drugs.
reaches every inch inside the cells.  Many enzymes inside the peroxisomes
 Cytoskeleton is a dynamic network built by catalyze Redox (reduction-oxidation)
interlinking protein filaments. It is reactions, which will generate hydrogen
composed of three main components, actin peroxide (H2O2) as a dangerous
filaments, intermediate filaments, and
microtubules.  Lysosomes
 Once a part of the cytoskeleton contracts or  Lysosome is a membrane-bounded sphere
extends, it deforms the cells and allows cells full of digestive enzymes and works like a
to change their shapes and movement. recycling center in the cell.
 microtubules  These enzymes can break down whatever
 actins substance entering the lysosomes into raw
 intermediate filaments materials (like amino acids, nucleotides,
lipids, and sugars), so the cell can reuse
 Nucleus these raw materials to build new organelles.
 The nucleus (plural: nuclei) is a membrane-
bound organelle that stores most of our  Endoplasmic Reticulum
genetic information (genome).  Endoplasmic reticulum (ER) is an internal
 The key feature that separates eukaryotic membrane that forms branching networks
cells (animals, plants, and fungi) from of many interconnected sacs and tubes.
prokaryotic cells (bacteria and archaea) is  There are two types of ER: rough ER and
the presence of a nucleus. smooth ER.
 Nucleolus:  The outer side (facing the cytosol) of the
 Nucleolus (plural: nucleoli) is a structure rough ER is studded with ribosomes. Under
inside the electron microscope, the dense granular
 the nucleus. ribosomes gave the name of “rough” ER.
 Nucleolus is known as the site of ribosome
  After endocytosis, the endosome can carry
 Golgi Apparatus its cargo to different places in the cell.
 Golgi apparatus (or Golgi) consists of several
stacks of membrane-bound cisternae (sacs).  Chromosome
 Golgi apparatus usually locates close to the  When the cells prepare for the cell division,
ER. It receives the raw protein products each DNA thread is organized into a much
from the ER, modifies them (for example, compact structure, called “chromosome”.
adding tags made by sugar chains), and  Every human cell has 23 pairs of
exports the proteins to a variety of chromosomes (1-22, and X or Y).
destinations.  A chromosome is formed by wrapping DNA
 The transportation of proteins is done around histone proteins into a core
within small bubbles, called vesicles. complex, called a nucleosome.
 The vesicles are generated by budding from
the membrane of the ER and Golgi. Centrosomes
 Centrosomes are organelles that only
 Ribosomes appear during mitosis and serve as the main
 Ribosomes are the places where proteins microtubule organizing center (MTOC).
are synthesized in our cells.  Each cell has two centrosomes. They move
 • Ribosomes consist of two major toward the opposite positions of the cells
components: the small and large ribosomal when the mitosis starts.
subunits. They are assembled by proteins  The microtubules extend from the
and ribosomal RNA (rRNA). centrosome and attach to the centromeres
 • Ribosomes translate mRNA into of sister chromatids. Both centromeres
polypeptide chains, which fold and retrieve their microtubule at the same time
assemble into proteins. to split the sister chromatids apart and
move into new cells.
TEMPORAL CELL FOR SPECIFIC TASK
Sister chromatids
Autophagosome  Sister chromatids are X-shaped
 Autophagosome is a temporary organelle chromosomes that remain attached at a
for autophagy. centromeric region (centromere) after DNA
 Autophagy (aka “self-eating”) is a process duplication.
that cells recycle some of their existed  Sister chromatids will be split into two
proteins and organelles identical chromosomes during mitosis.
 due to the shortage of nutrient supply.
 Damaged proteins or organelles will be put Unique Cell Organelles in the Plant cells
on a
 “Garbage tags”. The cell recognizes the tags Cell wall
and packs these recycle materials into  Cell wall is an extra layer of structural
autophagosomes.
support and protection outside the cell
membrane of plant cells.
Endosome
 Endosome is a membrane-bound temporary  Cell wall is made of cellulose, a polymer
organelle for engulfing the stuff outside of type of sugars.
the cell.  The structural support of cell walls
 Endosomes are formed by the invagination allows plants to
of the cell membrane, a process called  grow to great heights (like pine trees).
“endocytosis.” Wood is made of the reminded cellulose
 fibers of cell walls after the death of ✓Prokaryotic cells lack membrane-enclosed
matured xylem tissues of woody plants. organelles (including a nucleus)

Vacuole Modern Cell Theory

 Vacuole is a membrane-bound organelle  All living things are made up of cells.
that contains a mass of fluid.  Cells are the smallest working units
 Large, central vacuole is only present in of all living things.
the plant cells.  All cells come from preexisting cells
 Vacuole serves as a storage space for through cell division.
plant cells. It can store a variety of
nutrients (including sugars, minerals, Examples of Cells
amino acids, nucleic acids, ions, and  Amoeba Proteus
special chemicals) that a cell might need  Plant Stem
to survive.  Bacteria
 Red Blood Cell
Chloroplast  Nerve Cell
 Chloroplasts are organelles that conduct
photosynthesis and produce energy for Prokaryotic Cell
the plant cells. • Do not have structures surrounded by
 Chloroplasts convert the light energy of membranes
the Sun into sugars (a process called • Few internal structures
“photosynthesis”) that can be used by • One-celled organisms, Bacteria
cells.
 Chloroplast plays an important role in Eukaryotic
plant innate immunity. • Have organelles surrounded by
membranes
CELL STRUCTURE AND TAXONOMY • Most living organisms

Definition of Cell Cell Organelles

•A cell is the smallest unit that is capable of • Nucleus
performing life functions. –1 Nuclear envelope
–Chromatin and DNA
Two Types of Cells –Nucleolus
• Prokaryotic Cell • Eukaryotic Cell • Mitochondria
–Double membrane
EUKARYOTES AND PROKARYOTES –Mitochondrial (maternal) DNA
• Eukaryotes – is typically larger and – “Powerhouse” of the cell
structurally more complex. It includes algae, • Food converted into energy
protozoa, fungi, higher plants, and animals. –Adenosine triphosphate (ATP)
✓Eukaryotic cells have a membrane-bound • Consumes Oxygen, produces CO2
nucleus and other organelles ✓Cristae – series of folds
• Prokaryotes ✓Matrix – semifluid substance
✓Bacteria are unicellular, and most of them
multiply by binary fission (Directs cell activities)
Nucleus • Lipids
- Separated from cytoplasm by nuclear • Nucleic acids
membrane
- Contains genetic material - DNA Lipids
• Hydrophobic molecules
Cell Organelles – Energy storage, membrane components,
signal molecules
• Endoplasmic Reticulum – Triglycerides (fat), phospholipids, waxes,
– Site where cell membrane and exported sterols
material is made
Carbohydrates
– Ribosomes •Sugars, storage (glycogen, starch),
(rough) - Make protiens Structural polymers (cellulose and chitin)
Smooth ER- lipids •Major substrates of energy metabolism

• Golgi Apparatus Nucleic Acids

– Recieves and modifies – Directs new • DNA (deoxyribonucleic acid) and RNA
materials encode genetic information for synthesis of
all proteins
• Lysosomes • Building blocks of life
– Intracellular digestion – Releases nutrients
– Breakdown of waste Water Molecule
• Polarity of H20 allows H bonding
• Peroxisomes • Water disassociates into H+ and OH-
– Hydrogen Peroxide generated and • Imbalance of H+ and OH- give rise to
degraded “acids and bases”
- Measured by the pH
• Cytosol • pH influence charges of amino acid groups
– Water based gel on protein, causing a specific activity
– Chemical reactions • Buffering systems maintain intracelluar
and extracellular pH
• Cytoskeleton
– Filaments (actin, intermediate and PROKARYOTIC CELL STRUCTURE (External)
microtubules) ❖Glycocalyx (sugar coat) – is a viscous,
– Movement of organelles and cell – gelatinous polymer that is external to the
Structure/strengthen cell cell wall and composed of polysaccharide,
polypeptide, or both.
• Vessicles ❖Flagella – are long filamentous
– Material transport appendages that propel bacteria.
– Membrane, ER, Golgi derived vessicles

Organic molecules of Cells

• Proteins
• Carbohydrates Four Arrangements of Flagella
✓Monotrichous (a single polar flagellum) ✓Cytosol – fluid portion of cytoplasm
✓Amphitrichous (a tuft of flagella at each ✓Cytoskeleton – provides support and
end of shape and assists in transporting substances
the cell) through the cell
✓Lophotrichous (2 or more flagella at one ✓Cytoplasmic streaming – helps distribute
pole of the cell) nutrients and move the cell over a surface
✓Peritrichous (flagella distributed over the
entire cell) ❖Endoplasmic reticulum – extensive
network of flattened membranous sacs or
❖Axial Filaments – bundles of fibrils that tubules called cisterns
arise at the ends of the cell beneath an ✓Rough ER - is continuous with the nuclear
outer sheath and spiral around the cell. membrane and usually unfolds into a series
❖Fimbriae – can occur at the poles of the of flattened sacs
bacterial cell, or they can be evenly ✓Smooth ER – extends from the rough ER
distributed over the entire surface of the to form a network of membrane tubules
cell.
❖Pili – usually longer than fimbriae and ❖Ribosomes – attached to outer surface of
number only one or two per cell. rough ER, which are also found free in the
✓Pili join bacterial cells preparation for the cytoplasm
transfer of DNA from one cell to another.
✓Also called sex pili ❖Golgi complex – first step in the transport
pathway
PROKARYOTIC CELL STRUCTURE ✓Transport vesicle – fuses with a cistern of
(Internal) the Golgi
• Plasma Membrane – encloses the complex, releasing proteins into the cistern
cytoplasm and is a phospholipid bilayer with ✓Transfer vesicle – proteins are modified
peripheral and integral proteins (the fluid and move from one cistern to another
mosaic model) ✓Secretory vesicles – detach from the
✓Selectively permeable cistern and deliver the proteins to the
✓Carry enzymes for metabolic reactions, plasma membrane
such as nutrient breakdown, energy
production and photosynthesis 2. Lysosomes – formed from Golgi
• Cytoplasm – the fluid component inside complexes and look like membrane-
the plasma membrane enclosed spheres
✓Is mostly water, with organic and 3. Vacuoles – is a space or cavity in the
inorganic molecules, DNA, ribosomes and cytoplasm of a cell that is enclosed by a
inclusions membrane called tonoplast

❖Plasma Membrane – is very similar in 4. Mitochondria – appear throughout the

function and basic structure of prokaryotic cytoplasm of most eukaryotic cells
cell ✓Cristae – series of folds
❖Cytoplasm – encompasses the substance ✓Matrix – semifluid substance
inside the plasma membrane and outside
the nucleus
5. Chloroplasts – a membrane-enclosed - Transports undigested material to cell
structure that contains both the pigment membrane for removal
chlorophyll and the enzymes required for - Cell breaks down if lysosome explodes
the light gathering phases of photosynthesis
Vacuoles
6. Peroxisomes – similar in structure to - Membrane-bound sacs for storage,
lysosomes, but smaller digestion, and waste removal
- Contains water solution
7. Centrosome – located near the nucleus, Help plants maintain shape
consist of two components pericentriolar
material and centrioles Chloroplast
✓Pericentriolar material – region of the - Usually found in plant cells
cytosol composed of a dense network of - Contains green chlorophyll
small protein fibers - Where photosynthesis takes place
✓Centrioles – a pair of cylindrical structure
s within the percentriolar material Genetics and Heredity

Chromosomes What is Genetics?

 In nucleus • Traits are characteristics. –Same hair color,
 Made of DNA eye color, or skin color.
 Contain instructions for traits & • Genetics is the science of heredity.
characteristics • Heredity is the study of the way traits are
passed on from parent to offspring.
Nucleolus
- Inside nucleus Variation
- Contains RNA to build proteins - The traits an organism inherits is
determined during the life process of
Mitochondria reproduction.
- Produces energy through chemical - More variation (differences) is found in
reactions – breaking down fats & sexual reproduction than by asexual
carbohydrates reproduction.
- Controls level of water and other materials - In sexual reproduction, the offspring
in cell resembles its parents but is also
- Recycles and decomposes proteins, fats, different from them.
and carbohydrates
Species and Chromosome Number
Golgi Bodies • The chromosome number (species
- Protein 'packaging plant' chromosome number) is the same from
- Move materials within the cell generation to generation within an
- Move materials out of the cell organism or species.
• Every species will have a chromosome
Lysosome number.
- Digestive 'plant' for proteins, fats, and –Human = 46
carbohydrates –Crayfish = 100
–Dog = 48 Chromosome
–Cat = 38 - The nucleus of a cell contains
–Pea = 14 chromosomes which carry instructions
–Fruit fly = 8 for the growth and development of an
organism. The chromosomes are made
Chromosome Arrangement of long strands of DNA.
• In a cell, chromosomes are arranged in
pairs. Allele
• A photograph or chart of chromosomes - The versions of genes are called alleles
arranged in pairs is called a karyotype. and may be different from each other.

Gregor Mendel Inheritance of Traits

• Today’s knowledge about genetics is a During fertilization, the male and female
result of genetic studies started by Gregor parents each contribute genetic information
Mendel in the middle 1800’s. (traits) to the zygote (fertilized egg).
• Because of his work, he is called the • One half of its genetic information from its
“father of genetics.” male parent and the other half from its
• Mendel did not know about but thought female parent.
that certain were responsible for traits from Genetic traits are carried in chromosomes.
parents to offspring genes, “factors” passed
Genetic Terms
The Gene-Chromosome Theory Homozygous Trait - Both genes for that trait
- This theory states that chromosomes are the same.
(found in the nucleus of the cell) are • A pea plant with two genes for tallness.
made of small units called genes. Heterozygous Trait - Both genes for that
- Genes carry hereditary information and trait are not the same.
are found at specific locations along • A pea plant with one gene for tallness and
chromosomes. one for shortness.

Alleles Genetic Terms

- Alleles are pairs of genes that carry the Genotype - The genetic makeup of an
same traits and are found at the same organism.
locations on pairs of chromosomes. Phenotype - The external appearance of an
- Each chromosome may contain several organism.
hundred genes.

DNA
- Containing genetic information to
enable an organism to manufacture all
the proteins required to develop and
maintain an organism when necessary.