Chapter 3
PERPETUATIO
N OF LIFE

PLANT
REPRODUCTION

THESE PARTS PRODUCE SEX CELLS
OR GAMETES IN THE FORM OF
OVULES AND POLLEN GRAINS.
THESE ARE THE REPRODUCTIVE
PARTS OF THE PLANTS:

FLOWER
IN FLOWERING PLANTS, SEX CELLS ARE
PRODUCED IN CERTAIN FLORAL ORGANS.

Peduncle: The stalk of a flower.
Receptacle: The part of a flower stalk where the parts of the flower
are attached.
Sepal: The outer parts of the flower (often green and leaf-like) that
enclose a developing bud.
Petal: The parts of a flower that are often conspicuously colored.
Stamen: The pollen producing part of a flower, usually with a
slender filament supporting the anther.
Anther: The part of the stamen where pollen is produced.
Pistil: The ovule producing part of a flower. The ovary often supports
a long style, topped by a stigma. The mature ovary is a fruit, and the
mature ovule is a seed.
Stigma: The part of the pistil where pollen germinates.
Ovary: The enlarged basal portion of the pistil where ovules are
produced.

THE MALE REPRODUCTIVE ORGAN IS CALLED
THE STAMEN WHICH HAS TWO PARTS: THE
ANTHER (PRODUCES THE POLLEN, WHICH
CONTAINS THE MALE SPERM CELLS) AND THE
FILAMENT (THAT HOLDS OR SUPPORTS THE
ANTHER)

THE FEMALE REPRODUCTIVE ORGAN IS
PISTIL. THE OVULES ARE EQUIVALENT TO THE
POLLEN GRAINS OF THE MALE
REPRODUCTIVE ORGAN. OTHER PARTS OF
PISTIL (STIGMA, STYLE, OVARY AND THE
OVULE)

TYPES OF REPRODUCTION IN PLANTS
SELF-FERTILIZATION/SELF-POLLINATION
OCCURS IN BISEXUAL ORGANISMS,INCLUDING MOST
FLOWERING PLANTS,NUMEROUS PROTOZOANS, AND
MENY INVERTRBRATES.THE MECHANISM IS OBSERVED
MOST OFTEN IN SOME LEGUMES SUCH AS PEANUTS.IN
OTHER LEGUMES LIKE SOYBEANS, THE FLOWERS OPEN
AND REMAIN RECEPTIVE TO INSECT CROSS POLINATION
DURING THE DAY;IF THIS NOT ACCOMPLISHED,THE
FLOWER MAY SELF-POLLINATED AS THEY ARE
CLOSING.OTHER PLANTS THAT CAN SELF-POLLINATED
ARE ORCHIDS,PEAS,SUNFLOWERS,TRIDAX,ETC.

CROSS-FERTILIZATION
OCCUR BETWEEN MEMBERS OF THE SAME SPECIES,FOR
EXAMPLE,IT IS IMPOSIBLE TO CREATE A HYBRID OF A CUCUMBER
AND A ZUCCHINI AS THEY SEPARATE SPECIES WITH IN THE SAME
FAMILY,HOWEVER,IT WOULD BE POSIBLE TO CROSS A ZUCCHINI
WITH ANOTHER SQUASH,LIKE PUMKIN AS THEY BELONG TO THE
SAME SPECIES.CROSS-FERTILIZATIO ON PLANTS WHERE THE
INSECTS ARE THE AGENTS
(APPLES,PLUMS,PEARS,RASPBERRIES,BLACKBERRIES,BLACKCURR
ANTS,STRAWBERRIES,RUNNER
BEANS,PUMPKINS,DAFFODILS,TULIPS,HEATHER,LAVENDER,AND
ETC. CROSS-FERTILIZATIO ON PLANTS WHERE WIND IS THE MAIN
AGENT(GRASS,CATKINS,DANDELIONS,MAPLE TREES, AND GOAT’S
BEARD)

ASEXUAL REPRODUCTION
A SINGLE INDIVIDUAL (PARENT) IS CAPABLE OF
PRODUCING OFFSPRING,AS A RESULT, THE
OFFSPRING THAT ARE PRODUCED ARE NOT
ONLY IDENTICAL TO ONE ANOTHER BUT ARE
ALSO EXACT COPIES OF THEIR PARENT. ALL
THESE METHODS OF REPRODUCTION WORK
WELL.HOWEVER, THEY DO NOT MAKE IT
POSSIBLE FOR PLANTS TO MOVE TO NEW
LOCATIONS.IN ADDITION TO REPRODUCING
ASEXUALLY,MOST LAND PLANTS ALSO
REPRODUCE SEXUALLY.

A) BINARY FISSION (“DIVISION IN HALF”)
IS A KIND OF ASEXUAL REPRODUCTION.ANOTHER TYPE OF
FISSION IS MULTIPLE FISSION,WHICH IS ADVANTAGEOUS TO THE
PLANT LIFE CYCLE.MULTIPLE FISSION,AT THE CELLULAR LEVEL OF
OCCURS IN MANY PROTIST.
B) BUDDING
INVOLVES THE GROWTH OF A SMALL BULB-LIKE PROJECTION
CALLED BUD.IT GROWS AND DETACHES ITSELF FROM THE
PARENT CELL TO GROW INDEPENDENTLY INTO A NEW
ORGANISM.
C) FRAGMENTATION
INVOLVES BREAKING DOWN OF FILAMENTS INTO FRAGMENTS
THAT GROW IN TO YOUNG ONES.

D) ARTIFICIAL VEGETATIVE PROPAGATION
THE PROCESS OF PROPAGATING PLANTS THROUGH
ARTIFICIAL METHODS IS CALLED ARTIFICIAL PROPAGATION.THE
DIFFERENT METHODS OF ARTIFICIAL PROPAGATION ARE
GRAFTING,CUTTING,LAYERING, AND TISSUE CULTURE
I. GRAFTING
THE METHOD WHICH INVOLVES DEVELOPMENT OF NEW
VARETIES OF FRUIT PLANTS.
II.CUTTING
INVOLVES PLANTING A YOUNG CUTTING OF THE STEM WITH
BUDS INTO MOIST SOIL.
III.LAYERING
INVOLVES BENDING OF A YOUNG STEM TOWARDS THE
GROUND AND LET IT GROW UNDER THE SOIL.
IV.TISSUES CULTURE
A MASS OF TISSUE IS SELECTED FROM THE GROWING TIP OF
PLANT. THIS IS TERMED AS CALLUS

E) NATURAL VEGETATIVE REPRODUCTION
ASEXUAL REPRODUCTION IS ALSO USED IN AGGRICULTURE
AND HORTICULTURE TO PROPAGATE A PARTICULARLY DESIRABLE PLANT.
MOST ROSES AND POTATOES,ARE VEGETATIVELY PROPAGATED.
1) STOLONS
ARE STEMS WHICH GROW AT THE SOIL SURFACE OR JUST BELOW
GROUND THAT FORM ADVENTITIOUS ROOTS AT THE NODES, AND NEW
PLANTS FROM THE BUDS.
2) RHIZOMES
ARE ALSO IMPORTANT REPRODUCTIVE SRUCTURES, PARTICULARLY
IN GRASS AND SEDGES.IT INVADE AREAS NEAR THE PARENT PLANT, AND
EACH NODE CAN GIVE RISE TO A NEW FLOWERING SHOT.
3) SUCKERS
IS A PLANT GROWING NOT FROM A SEED BUT FROM
A MERISTEM OF THE ROOT AT THE BASE OR AT A CERTAIN DISTANCE
FROM A TREE OR SHRUB.

4) ADVENTITIOUS LEAVES
ADVENTITIOUS BUDS DEVELOP FROM PLACES OTHER THAN A SHOOT APICAL
MERISTEM, WHICH OCCURS AT THE TIP OF A STEM, OR ON A SHOOT NODE, AT THE LEAF AXIL, THE
BUD BEING LEFT THERE DURING THE PRIMARY GROWTH.
5) APOMIXIS
AS REPLACEMENT OF THE NORMAL SEXUAL REPRODUCTION BY ASEXUAL REPRODUCTION,
WITHOUT FERTILIZATION.
F) SEXUAL REPRODUCTION
INVOLVES TWO FUNDAMENTAL PROCESSES: MEIOSIS, WHICH REARRANGES
THE GENES AND REDUCES THE NUMBER OF CHROMOSOMES, AND FERTILIZATION, WHICH
RESTORES THE CHROMOSOME TO A COMPLETE DIPLOID NUMBER. IN BETWEEN THESE TWO
PROCESSES, DIFFERENT TYPES OF PLANTS AND ALGAE VARY, BUT MANY OF THEM, INCLUDING
ALL LAND PLANTS, UNDERGO ALTERNATION OF GENERATIONS, WITH TWO DIFFERENT
MULTICELLULAR STRUCTURES (PHASES), A GAMETOPHYTE AND A SPOROPHYTE.
I. CONIFEROUS TREES
A GROUP OF PLANTS CALLED GYMNOSPERM DEVELOPED WIND BORNE
POLLEN LIKE THE CYCADS, GINKOS AND NEEDLE-BEARING TREES SUCH AS PINES AND
REDWOODS.
II. THE DEVELOPMENT OF FLOWER
A NEW GROUP OF PLANTS, THE ANGIOSPERMS,APPEARED ABOUT 110
MILLION YEARS AGO. THESE PLANTS DEVELOPED A NUMBER OF STRUCTURAL
INNOVATIONS, THE MOST STRIKING OF WHICH IS THE FLOWER.

ORGANS OF PLANTS
THE ORGANS OF PLANTS ARE DIVIDED INTO VEGETATIVE AND
REPRODUCTIVE .THE VEGETATIVE ORAGANS ARE THE LEAVES,
STEM, AND ROOTS. THE LEAVES TAKE CARE FOR FOOD
MANUFACTURE AND TRANSPIRATION. THE STEM SUPPORTS THE
LEAVE AND PARTS OF THE PLANT. THE ROOTS ABSORB WATER
AND MINERALS AND ANCHOR THE PLANT TO THE SOIL.THE
REPRODUCTIVE ORGANS ARE RESPONSIBLE FOR THE
PERPETUATION OF THE PLANT. THESE ARE THE FLOWERS, FRUIT
AND SEEDS.
I. FLOWER HAS TREE MAIN ORAGANS,NAMELY:ESSENTIAL
ORAGANS WHICH FUNCTION FOR ATTRACTION;AND THE
ACCESSORY ORGANS WHICH PERFORM FUNCTIONS LIKE SUPPORT
AND PROTECTION

Most animals are capable of complex
and relatively rapid movement
compared to plants and other
organisms. Most reproduce sexually, by
means of differentiated eggs and
sperm. Most animals are diploid,
meaning that the cells of
adults contain two copies of
the genetic material.

The Animals which give birth
to live offspring are called
live-bearing or viviparous.
The animals which lay eggs
are called egg-laying or
oviparous.

Live-bearing
or
viviparous

Egg Laying
or
Oviparous

Asexual
Reproduction

Parthenogenesis

Example of Parthenogenesis

Budding
What is budding?
Budding is a type of asexual
reproduction. It is most
commonly associated with
bacteria and yeast, but some
animal species reproduce via
budding, too. A parent
organism creates a bud from
its own cells, which then
form the basis of the
offspring organism and
develop into an organism
resembling the parent.

Fragmentation
What is Fragmentation?
Fragmentation is a form of
asexualreproduction where a new organism grows
from afragment of the parent.
Each fragment develops into a fully grown
individual. Fragmentation is seen in many
organisms such as animals (some annelid worms
and sea stars), fungi, and plants.

Binary Fission
What is a binary fission?
- Binary fission is the primary method of
reproduction of prokaryotic organisms. In
protists, binary fission is often differentiated
into types, such as transverse or longitudinal,
depending on the axis of cell separation.
- Asexual reproduction in free-living
species usually involves nuclear division
and the division of the cell into two
identical daughter cells of equal size by
binary fission.

Example of
Binary
Fission

Sexual
Reproduction

Example of Hermaphroditism

Example of sequential hermaphroditism

How Genes
Work

A gene is a segment of DNA that encodes a
unique protein that performs a specialized
function in the cell. It is a functional unit of
heredity. A gene is capable of storing
information and capable of self-replication
and can undergo mutations. It acts as
instructions to make molecules called
proteins. In humans, genes vary in size from a
few hundred DNA bases to more than 2 million
bases. The Human Genome Project has
estimated that humans have between 20,000
and 25,000 genes.

Every person has two copies of each gene, one
inherited from each parent. Most genes are the
same in all people, but a small number of genes
are slightly different between people. Alleles are
forms of the same gene with small differences in
their sequence of DNA
bases. These small
differences contribute
to each person’s unique
physical features

THE CHEMICAL
COMPOSITION OF DNA
• DNAmeans deoxyribonucleic acid
• Found within the nucleus of each cell
• Your DNA is like your thumbprint. No one else
in this world has exactly the same DNAas you.
• DNA holds the genetic information needed to
make and control all cellular activities within a
living organism.
• DNAhas four bases:Adenine(A), Guanine(G),
Thymine(T) and Cytosine (C)

• A and G are double-ring structures called
purines; T and C are single-ring structures
called pyrimidines.
• The nucleotide is the building block of DNA
~It is made up of four bases , a five carbon
sugar deoxyribose, and a phosphate
group.
• Humans have 3 billion bases,
• The order or sequence of these bases
determine the information available for
building and maintaining an organism.

DNAarefoundineverycellofa person’sbody.It
is mostly located in cell nucleus (NuclearDNA)
but a small amount of DNAfound in the
mitochondria(mitochondrialDNA/mtDNA).
Each strand in
the double helix
can serve as a
pattern for the
duplicating the
sequence of bases.

W
ATSON AND CRICK MODEL
In 1953, James Watson and Frances Crick
worked out that DNA is like a “double helix”.
The DNA is a double helix because of the two
strands which wind around each other. The
two sugar-phosphate backbones make up the
sides and the base pairs make up the rung or
steps of the winding staircase. The model
shows that paired nucelotide, which always
occur as A-T or G-C, are linked by hydrogen
bonds. This is called the complementary base

Why is DNA Important?
All the characteristics that you have are
affected by the DNA in your cells. It
controls the color of your eyes, hair,
complexion, height and many more.
These characteristics, are traits that can
be inherited. How traits appear in you
depends on the kind of proteins your
cells make. DNAstores the blueprints
for making proteins.

How DNA Copies Itself
Step 1: an enzyme breaks the bond
between the nitrogen bases. The two
strands of DNAsplits.
Step2: The bases attach to each strand
then pair up with the free nucleotides
found in the cytoplasm
Step 3: The complementary
nucleotides join to form new strands.

The DNA replication is known as semi-
conservative replication because one of
the old strands is conserved in each
daughter molecule.

Mitochondrial DNA
Mitochondria also have a small amount of their own
DNA. This genetic material is known as Mitochondrial
DNA. Mitochondria are structures within cells that
convert the energy from food into a form that cells can
use. Each cell contains hundreds to thousands of
mitochondria which are located in the cytoplasm.
Mitochondria also produces energy called oxidative
phosphorylation. This process uses oxygen and
simple sugars to create adenosine
triphosphate(ATP). A set of enzyme complexes,
designated as I-V, carry out oxidative phosphorylation
within mitochondria.

Mitochondrial DNAcontains 37 genes, all of
which are essential for normal mitochondrial
function. 13 of these genes provide
instructions from making enzymes. The
remaining genes provide instructions for
making molecules called transfer
RNAs(tRNAs) and ribosomal
RNA(rRNAs) which are chemical cousins
of DNA. These types of RNA help assemble
protein building blocks(amino acids)into
functioning proteins.

DNA RNA
Function Stores genetic
information
Involved in protein
synthesis
Location Remains in the nucleus Leaves the nucleus
Structure Double helix Usually single strand
Sugar Deoxyribose Ribose
Pyrimidines Cytosine, Thymine Cytosine, Guanine
Purines Adenine, Guanine Adenine, Guanine
What is RNA?
RNA stands for ribonucleic acid. RNA is a long
strand made up of a building block called nucleotides.
RNAhas a single chain and does not entwine in a
double helix.

Protein Synthesis
Part I- Transcription
1. mRNA travels from the cell’s cytoplasm into the nucleus
2. In the nucleus, DNAunzips
3. mRNA nucleotides float into unzipped DNAfollowing
the order of the nitrogenous bases
4. Nitrogenous base pairing in the chart below
5. mRNA carries DNA’s code, in its strand, out into
cytoplasm
6. In the cytoplasm mRNA joins with tRNAfor next step,
translation
7. Nitrogenous Base Pairing

DNA RNA
G C
C G
T A
A U

Part II- Translation
1. mRNAtravels to and joins to a ribosomal unit at
the 5’untranslated region.
2. AtRNAcarrying a “start” codon and the amino
acid attaches to the codon of mRNA
3. The ribosome moves in the 3’direction down the
mRNA by three bases of one codon shifting the
tRNAand protein(polypeptide chain)
4. tRNAejected from the ribosome.
5. Process continues until a “stop” codon is reached
which finishes the process releasing the protein.