What to Study – Reproduction
Differenced between asexual and sexual reproduction
- Asexual reproduction uses one parent while sexual reproduction uses two parents.
- Asexual reproduction uses mitosis while sexual reproduction uses meiosis.
- Offspring produced as a result of asexual reproduction are genetically identical to parent while offspring produced as a result of sexual reproduction are NOT genetically identical to parent.
- Sexual reproduction uses gametes while asexual reproduction does not use gametes.
Differences between mitosis and meiosis
- Mitosis produces 2 daughter cells while meiosis produces 4 daughter cells.
- Mitosis is used to produce somatic cells while meiosis is used to produce gametes
- Mitosis produces cells with the SAME # of chromosomes while meiosis produces cells with HALF the # chromosomes
- Mitosis has one division while meiosis has two divisions.
- Mitosis is involved in asexual reproduction and meiosis is involved in sexual reproduction.
- Daughter cells of mitosis are genetically identical to each other while the daughter cells of meiosis are NOT genetically identical to each other
Mitosis Phases
- Interphase: chromosomes replicate
- Prophase: spindle fibers start to form, nuclear membrane starts to break down, centrioles start moving to opposite poles
- Metaphase: chromosomes line up in the MIDDLE
- Anaphase: Chromatids separate and start to pull away from each side
- Telophase: nuclear membrane reforms around each set of chromosomes, cytokinesis begins
CYTOKINESIS:
o Animal cells – cell membrane pinches in to separate the cells
o Plant cells – CELL PLATE forms to separate the cells
Types of Asexual Reproduction
- Binary fission: equal division of cytoplasm (ameba, paramecia, bacteria)
- Budding: unequal division of cytoplasm (yeast, hydra)
- Sporulation: organism releases spores that will eventually develop into a new organism (fungi)
- Regeneration: a lost body part grows back OR part of an organism grows into a new organism (starfish, lizards)
- Vegetative propagation: asexual reproduction of plants
o Runners: stems found on top of soil (strawberries, pumpkins, watermelon)
o Tubers: part of underground stem that stores food (potatoes)
o Bulbs: part of underground stem that stores food (onions, tulips)
- Artificial vegetative propagation: a result of human activity
o Cuttings: cutting off a part of a plant and letting it grown into a new plant
o Grafting: attaching the stem of one plant to another plant
Binary fission Budding Regeneration Vegetative propagation Sporulation
Male Reproductive System
- Testes: produce sperm and testosterone
- Scrotum: sac that holds the testes to keep them slightly cooler than the rest of the body
- Vas deferens: tubes that transport sperm from the testes to the urethra
- Seminal vesicles, Prostate glands: release fluid that makes up semen
- Urethra: transports sperm and urine out of the body
- Penis: inserts sperm into the female
Female Reproductive System
- Ovaries: produces eggs and the hormones estrogen and progesterone
- Oviduct/Fallopian tubes: tube that eggs are released into
o Ovulation: the release of an egg into
- Uterus: muscular organ where embryo develops
- Cervix: opening of the uterus
- Vagina: birth canal
Fertilization
- Fertilization: joining of egg cell and sperm cell to produce a zygote
- Two types
o External fertilization: occurs outside the female
§ Aquatic organisms
§ Many eggs are released to increase the chance of fertilization
o Internal fertilization: occurs inside the female
§ Terrestrial organisms
§ Not as many eggs are released because they are well protected
Embryonic Development
1. Zygote undergoes cleavage (mitosis)
- No cell growth
2. Morula is produced (solid ball of cells)
3. Blastula is produced (hollow ball of cells)
4. Gastrula is produced
- 3 layers: endoderm (inner layer), mesoderm (middle layer), ectoderm (outer layer)
5. Differentiation: cells become specialized (have a specific function)
Zygote cleavage cleavage morula blastula gastrula
External Development
- Aquatic and some terrestrial organisms
- Yolk: Source of food for embryo
- Amniotic fluid: protects embryo
Internal Development
- Placenta: provides nourishment for embryo
o Nutrients and oxygen to the fetus (also drugs and alcohol)
o Metabolic wastes (CO2) from the fetus
- Umbilical cord: transports substances between the fetus and the mother
- Amniotic fluid: protects and cushions the fetus
Sexual Development in Plants
- Structure of the flower
o Pistil: female part of flower
§ Stigma – where pollen STICKS to
§ Style
§ Ovary: contains ovules where eggs are found
o Stamen: male part of flower
§ Anther: produces pollen (contain sperm nuclei)
§ Filament: holds anther up
o Petals: brightly colored to attract pollinators
o Sepals: protect the flower
- Pollination: when pollen sticks to the stigma
o Pollen tube forms down the style into the ovary
o Sperm nuclei travel down the pollen tube into the ovule to fertilize the egg
o Fertilization occurs in the ovule
o Ovary turns into the fruit
o Ovules develop into seeds
- Seed structure
o Plant embryo
o Seed coat: protects the plant embryo
o Cotyledon: food source for the embryo