Reproduction

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Reproduction

• Chapter 11.1

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Recall the Two Important Questions we asked.

• What is the significance of Mitosis?
• Why do Chromosmes come in Pairs?

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Asexual vs SexualReproduction
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Characteristics ofASEXUAL REPRODUCTION

• One Parent
• Genetic Continuity Identical Offspring
• Many Offspring Quickly
• Less Maturation Time
• Nuclear Division MITOSIS

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Types of Asexual Reproduction
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Binary Fission (splitting in two)
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Fragmentation - (pieces)

• Fragmentation- A kind of reproduction where the
  body breaks into several pieces and the pieces
  develop into complete adults.

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Fragmentation - (pieces)
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BUDDING
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Budding

• New individuals split off of the original
  organism.

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CytoplasmDividesUnequally
bud
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Multicellular Budding - sponge
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Parthenogenesis
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Parthenogenesis a process in which a female
produces an egg that develops into an adult
without ever being fertilized.
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Cloning
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More about cloning during Chapter 15!
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Sexual Reproduction

• Requires two parents (cells)
• Union of special cells called GAMETES
• Sperm and Eggs or pollen and ovum
• Provides GENETIC VARIATION
• Usually mature more slowly

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Types of Gametes

• Egg Sperm
• Pollen Ovum

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Sexual Reproduction

• Advantages
• Genetic variation
• Genetically diverse populations are able to
  withstand changes and disease better.
• Disadvantages
• Need to expend energy looking for mate
• Produce fewer offspring.

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Hermaphrodites

• Organisms with ovaries and testes
• Produce both eggs and sperm.

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Earthworms have testes and ovaries
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Chromosome review

• A chromosome is an X shaped object that contains
  DNA.
• Within the DNA lies the codes for every
  characteristic of a living thing.

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Chromosome review

• Every chromosome consists of two identical halves
  called sister chromatids
• The chromosome has a backup copy of the DNA.

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Chromosomes

• Genes are located on located on chromosomes.
• Each chromosomes contains thousands of genes.
• A gene controls a specific trait such as your
  height or hair color.

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Chromosome numbers

• Every species has a specific number of
  chromosomes.
• Humans have 46 chromosomes or 23 pairs of
  chromosomes.

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Chromosome numbers

• Mosquitos have only 6 chromosomes in each cell.
• How many pairs of chromosomes does a mosquito
  have?

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Haploid vs. diploid cells

• Diploid cell- A cell that has two copies of each
  chromosome.
• This would include all somatic/body cells
• New cell will have an identical copy of DNA
• Diploid cells are produced by mitosis
• Mitosis is an asexual process.
• We call these cells 2N cells.
• Examples would include liver cells, etc.

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Haploid vs. diploid cells

• Haploid cells- Have only one (half) set of
  chromosomes.
• This includes ONLY GAMETES (egg/sperm).
• The two gametes will combine to create a new
  organism with full set of chromosomes (half from
  mom, half from dad).
• Haploid cells are created through meiosis.
• Meiosis is a sexual process.
• We call haploid cells 1N or N

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Haploids vs. diploid cells
SPECIES HAPLOID (N) DIPLOID (2N)
HUMANS 23 ( chromosomes in sperm/egg) 46 ( chromosomes in somatic/body cells)
MONKEY 42
CORN 10
CATS 38
FRUIT FLY 4
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HOMOLOGOUS CHROMOSOMES

• Homologous chromosomes- Each diploid cell has a
  pair of chromosomes known as homologous
  chromosomes.
• They are similar in shape size and genetic
  make-up.
• In each homologous pair one chromosome came from
  your mother and one from your father.

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Homologous pairs
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Autosomes vs. sex chromosomes

• Autosomes- Chromosomes with genes that do not
  determine the sex of an individual.
• Sex chromosomes- Chromosomes that do determine
  the sex of an individual.

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Autosomes vs. sex chromosomes
Sex chromosomes (Female)