SEXUAL REPRODUCTIONForm of reproduction which
requires two parents, egg and sperm
Produces offspring that are genetically different from each other and any other member of the species
Can occur in plants and animals
MEIOSIS
The process that produces gametes ``sex cells`` – egg in female and sperm in male with half the number of chromosomes as body cells.
HAPLOID VS. DIPLOID
Haploid = half the genetic content (n)
Diploid = genetic equal to the parent. Full genetic content (2n)
Haploid Diploid
8 STAGES OF MEIOSIS
Prophase IMetaphase I
Anaphase ITelophase I
Prophase IIMetaphase II
Anaphase IITelophase II
MEIOSIS I MEIOSIS II
Question?
Mitosis Meiosis
Where does it take place?
How many cells are produced?
What happens to the number of Chromosomes?
Type of Reproduction?
Question?
Mitosis Meiosis
Where does it take place? In Body Cells
In Sex organs
How many cells are produced?
2 daughter cells
4 daughter cells
What happens to the number of Chromosomes?
Same Number of
Chromosomes as Parent
½ the number of
Chromosomes as Parent
Type of Reproduction?
Asexual Reproductio
n
Sexual Reproductio
n
FERTILIZATION (THE UNION OF EGG AND SPERM TO CREATE A ZYGOTE) MAY OCCUR:
Outside the bodies of the parents – External Fertilization
OR
Inside the mothers body where the developing embryo is nourished for a period of time –
Internal Fertilization
SEXUAL REPRODUCTION IN:
1. Mosses
External fertilizationWater allows the egg
and sperm cells to meet
Has both sexual and asexual stages in its life cycle
SEXUAL REPRODUCTION IN:
2. Flowering PlantsExternal fertilizationPollination - Transfer of
male gametes in structures called pollenPollen adheres to the “sticky” female part
of the plant and male gametes fertilize the eggs
seeds contain the embryo and are usually protected in fruit or cone
SEXUAL REPRODUCTION IN:
3. InsectsIn many insects, the male deposits a package of sperm inside the female.
Insects often change a great deal between hatching and adulthood - METAMORPHOSIS
2 TYPES OF METAMORPHOSIS
Four 4 stagesEgg-Larva-Pupa-Adult
The adult and the larva look completely different
Ex. Butterfly
Three 3 stagesEgg-Nymph-Adult
The adult and the nymph resemble one another
Ex. Grasshopper
Complete Metamorphosis
Incomplete Metamorphosis
MAJOR STAGES OF HUMAN
DEVELOPMENTFertilizationFirst Trimester
(weeks 1-12)Second Trimester
(weeks 13-24)Third Trimester
(weeks 25-38)
FIRST TRIMESTER (WEEKS 1-12)Movement from fallopian tube to
uterus occursZygote now called an embryo,
attaches to the uterine wallPlacenta and amniotic sac formEmbryo becomes a fetus at about 8
weeksBy the end of this trimester all
major organs have begun to develop
SECOND TRIMESTER (WEEKS 13-24)
Skeleton formsNervous system
begins to functionMother begins to
feel movementOrgans continue to develop
GREGOR MENDEL Mid-1800s, Austrian
priestExperimented with
pea plantsConcluded traits
were tiny units of inheritance received in pairs, one from each parent
FRANCIS WATSON AND JAMES CRICK
1953Described the
“double helix” structure of DNA and how it replicates
Won a Noble Prize
THE HUMAN GENOME PROJECT
1986-2003Genome: consists of the full
set of genetic material that makes up an organism.
Scientist around the world collaborated to make a map to identify genes
Used to identify genetic diseases
ALLDERDICE SYNDROME Identified in an isolated community of
Sandy Point where a high incidence of birth defects were noted, believed to be due to a lack of genetic diversity
Symptoms included abnormalities resulting in mental and physical challenges
Dr. Allderdice of Memorial University determined that it was caused by part of one chromosomes being reversed.
DOWN’S SYNDROME•Frequently occurring chromosome Mutation•Individual has an extra 21st chromosome•Generally results in shorter stature, characteristic facial features and may be prone to developing other diseases
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