Reproduction and Development

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Reproduction and Development

• Aim To elaborate on the different types of
  reproduction
• Do Now Explain the differences between asexual
  and sexual reproduction

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• Species a group of closely related organisms
  that share certain characteristics and can mate
  and produce viable offspring

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Asexual Reproduction

• Asexual Reproduction can happen in different ways
• Budding an outgrowth later comes off and becomes
  a new individual
• Binary Fission The parent divides into two
  daughter cells

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Asexual Reproduction

• Bacteria, algae, most protozoa, yeast,
  dandelions, and flatworms all reproduce
  asexually.
• Offspring are clones of parents

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Sexual Reproduction

• Sex cells (gametes) egg or sperm cells
• Fertilization process where egg and sperm cells
  are joined together
• Sperm sex cell from the father
• Egg sex cell from the mother
• Offspring will be similar to their parents, BUT
  NOT identical

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Cloning

• Cloning a way of making identical genetic copies
  100 of the DNA comes from one parent

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Cell Division

• Mitosis cells genetic material divides creating
  two complete sets of the cells genetic material
• IPMATC

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• Mitosis

All the cells DNA is found in the cell nucleus in
structures called chromosomes
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• Mitosis

When cells divide, the chromosomes appear, divide
and separate
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• Mitosis

Two new cells form with identical chromosomes to
the original cell
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Here are the main cell parts involved in mitosis-
Centrioles
Cell Membrane
Nucleolus
Chromatin network
Nuclear Envelope
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• MITOSIS can be divided into FIVE different
  stages

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

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• Remember the sequence IPMAT

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

• I
• P
• M
• A
• T

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Interphase occurs before mitosis begins

• Chromosomes are copied ( doubles)
• Chromosomes appear as threadlike coils
  (chromatin) at the start, but each chromosome and
  its copy (sister chromosome) change to sister
  chromatids at end of this phase

CELL MEMBRANE
Nucleus
Cytoplasm
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Interphase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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Prophase 1st step in Mitosis

• Mitosis begins (cell begins to divide)
• Centrioles (or poles) appear and begin to move to
  opposite ends of the cell.
• Spindle fibers form between the poles.

Centrioles
Sister chromatids
Spindle fibers
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Prophase
Plant Cell
Animal Cell
Spindle fibers
Centrioles
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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Metaphase 2nd step in Mitosis

• Chromatids (or pairs of chromosomes) attach to
  the spindle fibers.

Centrioles
Spindle fibers
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MITOSIS Metaphase -
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Chromosomes line up SINGLE FILEat the Equator
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Metaphase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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Anaphase 3rd step in Mitosis

• Chromatids (or pairs of chromosomes) separate and
  begin to move to opposite ends of the cell.

Centrioles
Spindle fibers
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MITOSIS Anaphase-
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Double stranded Chromosomes split to form TWO
single stranded chromosomes
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MITOSIS Anaphase
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Single stranded chromosomes move to opposite
poles
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Anaphase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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Aim What are the stages of mitosis? Do Now If
you had fallen this morning on the way to school,
how would your body repair itself? What process
would it use?
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Telophase 4th step in Mitosis

• Two new nuclei form.
• Chromosomes appear as chromatin (threads rather
  than rods.
• Mitosis ends.

Nuclei
Nuclei
Chromatin
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Telophase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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MITOSISOriginal Cell Divides to form TWO new
cells with the SAME number of chromosomes
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Cytokinesisoccurs after mitosis

• Cell membrane moves inward to create two daughter
  cells each with its own nucleus with identical
  chromosomes.

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http//www.icompositions.com/music/song.php?sid11
0420 http//www.nclark.net/MitosisMeiosis
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Animal Mitosis -- Review
Interphase                                                              Prophase                                                             
Metaphase                                                              Anaphase                                                             
Telophase                                                              Cytokinesis                                                             
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Plant Mitosis -- Review
Interphase                                                              Prophase                                                             
Metaphase                                                              Anaphase                                                             
Telophase                                                              Cytokinesis                                                             
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REMEMBER!

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

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Meiosis
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Meiosis

• Cell division to form the gametes, sperm (male
  gamete) and egg (female gamete).
• Normal cells are diploid 2 copies of every gene.
• Gametes are haploid 1 copy of every gene
• Need to choose 1 copy of each gene randomly.

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• Somatic (body) cells have 46 chromosomes -
  Diploid
• Sex (egg and sperm) cells have 23 chromosomes -
  Haploid

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Why have sexual reproduction?

• Shuffling of alleles between parents and
  offspring leads to new combinations.
• Bad combinations die without reproducing good
  combinations survive and reproduce more
  offspring.

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• Aim What are the differences between mitosis and
  meiosis?
• Do Now List and explain the steps of mitosis

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• http//www.classroom20.com/video/649749Video1048
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Overview

• Start with a diploid cell, with 2 copies of each
  chromosome, one form each parent.
• Use 2 cell divisions
• Meiosis 1. First separate the homologues
• Meiosis 2. Then separate the 2 chromatids.
• The stages of meiosis have the same names as in
  mitosis

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Meiosis 1

• Two important events in meiosis 1
• crossing over in prophase
• pairing of homologues in metaphase.
• Crossing over. Homologues break at identical
  locations, then rejoin opposite partners. Results
  in mixing of the genes you inherited from your
  parents.

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More Meiosis 1

• At metaphase, the pairs of homologous chromosomes
  line up side by side. This does not happen in
  mitosis of meiosis 2.
• At anaphase of meiosis 1, the pairs of homologues
  are pulled to opposite poles by the spindle.

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Result of Meiosis 1

• Go from 1 cell to 2 cells. Each daughter cell
  contains 1 copy of each chromosome
• For humans start with one cell containing 46
  chromosomes (23 pairs) to 2 cells containing 23
  chromosomes.
• As a result of crossing over, each chromosome is
  the mixture of the original homologues.

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Meiosis 2

• Meiosis 2 is just like mitosis
• No replication of DNA between meiosis 1 and
  meiosis 2.
• Chromosomes line up individually on the equator
  of the spindle at metaphase.
• At anaphase the centromeres divide, splitting the
  2 chromatids.
• The one-chromatid chromosomes are pulled to
  opposite poles.

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More Meiosis 2
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Summary of Meiosis

• 2 cell divisions.
• Start with 2 copies of each chromosome
  (homologues), each with 2 chromatids.
• In meiosis 1, crossing over in prophase mixes
  alleles between the homologues.
• In metaphase of meiosis 1, homologues pair up,
  and in anaphase the homologues are separated into
  2 cells.
• Meiosis 2 is just like mitosis. A total of 4
  cells, each with 1 copy of each chromosome,

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Life Cycles

• Meiosis converts a diploid cell into haploid
  cells. Fertilization combines the 2 haploid
  gamete cells (sperm and egg) back into a diploid
  cell.
• Eukaryotes alternate between diploid and haploid
  stages. This is called the life cycle of the
  organism.

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Gamete Formation in Animals

• Differences between male and female gametes.
• In males, all 4 products of meiosis develop into
  sperm cells.
• In females, the cell divisions of meiosis are
  uneven most of the cytoplasm goes into 1 of the
  4 meiotic products, which becomes the egg. The
  other 3 meiotic cells are small polar bodies,
  which degenerate.

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• During Prophase I of meiosis, chromosomes undergo
  crossing over which is the exchange of genetic
  information

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Mitosis vs. Meiosis
Points of comparison Mitotic Division Meiotic Division
Number of cell divisions One 2
Exchange of genetic material between chromosomes No Yes
Number of functioning cells produced from original 2 4 sperm or 1 egg
Genetic makeup of final cells produced Same Highly variable
Function of cells produced in multicellular organisms Growth or replacement Combine to form zygote
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• Fertilization when sperm and egg combine

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• Zygote combination of gametes a cell that
  contains all of the genetic information needed by
  the offspring

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• The zygote divides by mitosis to form a
  multicellular organism

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• Recombination genes from both parents recombine
  when fertilization occurs
• This leads to a lot of variation

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• Differentiation cells become different from one
  another

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• Embryo organism in the early stage of development

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• Gene expression result of activated genes can
  be modified by interaction with the environment

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• Figure 21.21
• .
• Comparison of a brain from an infant with fetal
  alcohol syndrome (left) with a brain from a
  normal infant of the same age (right). The brain
  from the infant with FAS is significantly
  smaller, and the pattern of convolutions is
  obscured by glial cells that have migrated over
  the top of the brain. (Photographs courtesy of S.
  Clarren.)

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Female Reproductive System

• Ovaries produce egg cells and the hormones
  estrogen and progesterone
• Oviduct (Fallopian tube) attaches to ovary and
  leads to uterus egg cell is fertilized here
• Uterus where embryo develops into a fetus

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• Aim How does the body prepare for pregnancy?
• Do Now What is an ectopic pregnancy?

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Structure Function
Ovary Produces egg cells releases estrogen and progesterone
Oviduct Site of fertilization carries egg to uterus
Uterus Where embryo and fetus develop
Birth Canal (Vagina) Site where sperm enter passageway for birth of the baby
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• Placenta organ responsible for the passage (by
  diffusion) of nutrients and oxygen from the
  mothers blood to the fetus

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• Fetus an embryo after all the major organs have
  begun to form

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Hormones

• Follicle Stimulating Hormone (FSH)
• Estrogen
• Luteinizing Hormone (LH)
• Progesterone

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• Estrogen and progesterone influence the
  preparation of the lining of the uterus so a
  zygote can develop
• Progesterone maintains the uterine lining during
  pregnancy
• No zygote, estrogen and
• Progesterone decrease and
• The lining breaks down

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Hormones
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Female Reproductive Cycle
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MALEReproductive System
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Male Reproductive System
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• Testes organs that produce sperm cells
• Testosterone hormone produced by the testes
  associated with male sexual development and
  reproduction

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Sperm

• Males produce sperm cells continually
  throughout their reproductive lives.

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Sperm

• The midpiece of the sperm cell contains many
  mitochondria which are responsible for producing
  ATP for the tails lashing movement that propels
  the sperm through fluid.

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Spermatogenesis
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Male Sex Hormones

• Male Sex Hormones
• All the male sex hormones are called androgens.
  Androgens are made in the testicles and also in
  the adrenal cortex. The most abundant is
  testosterone!

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Testosterone

• Testosterone
• Is secreted for a short time during fetal
  development and for a short time after birth. It
  is not secreted again until puberty.
• Testosterone is responsible for the following
• Enlargement of the testicles and accessory organs
  and development of the male secondary sex
  characteristics.

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Male Secondary Sex Characteristics

• Body hair on face, chest, armpits, pubic
  region--sometimes, the growth of hair on scalp
  slows
• Enlargement of larynx, thickening of vocal cords
  which lowers the pitch of the voice
• Thickening of skin
• Muscles get larger, shoulders broaden, waist
  narrows
• Bones thicken and get stronger
• Cellular metabolism increases and red blood cell
  production increases
• Increase in libido (sex drive)

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Reproductive Technology

• Artificial Insemination

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• In-vitro fertilization

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• Amniocentesis