Download The Living Environment Unit 4 Reproduction and Development

The Living Environment Unit 4 Reproduction and Development
Species – Group of closely related organisms that can reproduce fertile offspring naturally.
* Reproduction continues the species.
TYPES OF REPRODUCTION
Asexual - ONE parent producing a genetically identical offspring (CLONE).
• Replicates it’s DNA then divides in two.
Sexual – TWO parents where offspring receives HALF the genes from each parent via GAMETES.
• Gametes – Sex Cells such as Sperm and Eggs that carry half the genetic material.
• Siblings are different due to unique combinations of genes
TYPES OF CLONES
Natural - Asexual (ex) Ameba, Bacteria Sexual (ex) Identical Twins – One fertilized egg
Sexual (ex) Identical Twins – One fertilized egg separates into two with identical
genes
Artificial – Inserting the complete nucleus genes of a cell from one organism into an egg
nucleus / genes.
without a
TWO TYPES OF CELL DIVISION
Cell Division – An orderly separation of one cell into two.
• DNA must replicate BEFORE cell divides.
I.) MITOSIS – (asexual) Produces TWO cells with IDENTICAL genes (Clones).
• One Cell Organisms use Mitosis to reproduce.
• Multicellular Organisms use Mitosis for growth, replacement and repair.
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•
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3 STEPS OF MITOSIS CELL DIVISION
Chromosomes (DNA) REPLICATE themselves, holding together in pairs. X
Chromosomes PAIRS SEPARATE apart, each going to each side of nucleus. / \
Cell DIVIDES into two identical cells with full identical genetic information. /
/
II.) MEIOSIS – (sexual) produces GENETIC VARIATIONS by dividing genes in half for
variation in sex cells and offspring.
* Genetic Diversity is important for survival of a species.
4 STEPS OF MEIOSIS SEX CELL DIVISION (Gamete production)
1) Chromosomes (DNA) REPLICATE themselves holding together in pairs. //// XX XX
2) Similar pairs may connect and EXCHANGE parts of genetic information. XX XX
3) Newly mixed chromosomes pairs go to OPPOSITE side of nucleus
XX XX
4) Cell DIVIDES taking HALF the genetic materials. XX
XX
4A) In Male Gamete formation - Cytoplasm divided evenly, forming 4 sperm cells
which carry HALF the genetic information
XX / / / /
XX / / / /
4B) In Female Gamete formation – Cytoplasm divided Unevenly, forming 1 egg cell and 3 useless cells,
all containing HALF the genetic information.
Xx / /
xx / /
/ /
/ /
Genetic variation (shuffling) in Meiosis can occur by:
A) Variation by Chromosome pair up (whole DNA strand)
Pg 65 Fig 4-8
B) Variation by exchange of genetic parts. (part of DNA strand) Pg 65 fig 4-9
Sexual Reproduction
Zygote - is a cell resulting from the joining of a sperm and egg (fertilization).
* Recombination – Genes from both parents recombine.
• Zygotes divide by MITOSIS
• A SHORT TIME AFTER FERTILIZATION, FACTORS INSIDE/OUTSIDE THE ZYGOTE TRIGGER
Differentiation – when Mitotic cells begin to become specialized by making specific proteins (skin cells,
nerve cells heart cells etc)
Gene Expression – Genes begin to actively produce its special protein, thereby showing the type of cell it will be.
• Gene Expression can be modified by external environment such as temperature & light.
HUMAN REPRODUCTION AND DEVELOPMENT
In most mammals, fertilization and development take place internally.
Female Reproductive System
Ovaries - Produce egg cells (gametes)
Produces hormones Estrogen - female hormone & Proestrogen – reproductive hormone
Oviduct – Tubes leading from ovaries to uterus. Fertilization takes place here.
Uterus – Where embryo develops into fetus.
Placenta – organ that forms in the uterine wall. Nutrients / O2 & waste / CO2 diffuse to/from fetus.
Birth Canal (vagina)- Where sperm enters and offspring exit.
Male Reproductive System
Testes – Produce sperm (gametes) and Testosterone (male hormone).
Penis – Where sperm and urine pass from body.
HORMONAL REGULATION
Testosterone – Male hormone that influences:
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•
Male Reproductive System
Facial hair, muscle growth, deep voice, male behavior
Estrogen/Proestrogen – Female hormone which influences:
• Female reproduction System
• Widens hips, breast development, female behavior.
Female Monthly Reproductive Cycle- About 28 days. An egg is released about day 14.Hormones prepare uterus wall to
hold fertilized egg. If no egg is fertilized, wall lining breaks down and is shed (period).
HUMAN DEVELOPMENT
First 2 Months – Mitotic division & cell differentiation. Placenta & fluid sac develops. Major organs are forming.
After 2nd Month – It becomes a Fetus.
APPLICATION OF REPRODUCTIVE TECHNOLOGY
Agriculture – Creating plants naturally resistant to insects and frost and producing plants through cloning.
• Artificial insemination – inexpensively breeding desired animals by Freezing sperm/egg and artificially
implanting animals.
Ecology – Allows man to preserve and build up endangered species of plants and animals. Can also control pest populations
without using chemicals.
Medicine – Infertile couples given fertility drugs or in vitro fertilization.
Technology such as ultrasound and Video cameras to view developing fetus.
Fetal cells can be analyzed for potential problems before birth.