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Sexual Reproduction
Review: What is Asexual Reproduction?
Sexual Reproduction
Review: What is Asexual Reproduction?
Only involves one parent
offspring are genetically identical to parent because the parent makes an exact copy of itself. (They are clones)
That is what we observed in mitosis.
Sexual Reproduction
What types of asexual reproduction did we read about?
Sexual Reproduction
What types of asexual reproduction did you read about?
Binary Fission:single celled organisms (bacteria, amoebas) divide into two identical daughter cells that are clones of the parent.
Budding:parent produces a small bud, or minatureized clone. Sometimes the clones detach (yeast) but sometimes they remain attached (coral).
Parthenogenesis unfertilized eggs mature into new organisms.
(some reptiles, some bees, komodo dragons, some sharks)
In bees, parthenogenesis is how male bees are born, whereas female queens and workers are produced from fertilized eggs.
This was first observed in sharks in 2001, when a female shark in captivity, separated from males for three years, got pregnant and had an offspring genetically identical to herself.
Spores:most common in fungi, algae, and plants.
example: mold
Vegetative Reproduction:does not involve seeds
Fragmentation:new individuals are formed from a piece of the existing parent.
(worms, starfish)
Grafting:part of one plant is joined with another plant so they can heal together and grow as a single plant.
Plant Tissue Cultures:plant cells placed in a petri dish with nutrients to grow
can use this to conserve endangered plant species
https://www.youtube.com/watch?v=AaN6uRvfPLY
Sexual Reproduction
What would happen if you put 10 drops of water on a piece of bread, sealed the bread in a bag, and stored the bread in a warm area for several days?
Would this count as sexual or asexual reproduction?
Sexual Reproduction
Sexual Reproduction:
usually involves two individuals
in humans and other mammals it always involves a male and a female
Sexual Reproduction in plants or animals is the union of two sex cells (gametes) to produce a new individual.
From the female: eggs or ova
From the male: sperm
The union of the sperm cell with the egg cell is called fertilization.
Sexual Reproduction
What do you think are some differences between asexual reproduction and sexual reproduction?
Sexual Reproduction
The offspring of sexual reproduction will have a mix of traits from both parents.
Do sex cells (gametes) go through mitosis?
Sexual Reproduction
Gametes are produced through a cell division process called meiosis.
In meiosis, the result is four daughter cells each with half the number of chromosomes of the parent cell.
diploid
haploid
Meiosis produces gametes. When a male gamete and a female gamete join, a new single cell is formed called a zygote. The zygote is the first cell of the new individual and will eventually form an embryo.
The embryo can develop inside the parent or outside in an egg.
Sexual Reproduction
Most animals have a distinct sex, male or female.
Hermaphrodites can produce both male and female gametes.
examples: worms and slugs.
Sequential hermaphrodites are species that are born as one sex but can then become the opposite.
example: clownfish
Clownfish schools consist of 1 large reproductive female, 1 smaller reproductive male, and numerous smaller nonreproductive females.
If the female dies or leaves, the reproductive male becomes a female and the largest of the nonreproductive males becomes the new reproductive male.
Sexual Reproduction
Make a model
Mitosis and Meiosis physical representation of each
you can use the same model as long as you can represent both processes.
Humans have 46 chromosomes, however you do not have to use 46 in your first cell. You can use two, four, or six in your first cell.
Use whatever model helps you understand the processes. This might include drawings, posters, skits, videos, 3D representations, etc.
Sexual Reproduction
Sexual Reproduction:
In animals:1. Your sex cells undergo meiosis to produce gametes with half of your genetic information. (Your parent cell has 46 chromosomes so your gamete will have 23)
2. A male gamete (sperm) joins with a female gamete (ovum/egg) to produce a zygote and then an embryo (with 46 chromosomes) which turns into a human.
The embryo might develop inside the parent or outside in an egg.
Sexual Reproduction
Sexual Reproduction:
In plants:Most plants produce both male and female gametes, some only produce one type.
1. A male gamete (pollen>found on stamen) joins with a female gamete (ovules> found in the pistil) to produce a zygote and then an embryo which turns into a seedling.
If plants have both gametes, they can transfer pollen themselves, known as selfpollination.
If pollen of one plant is carried to the stigma of another (by wind, water, or animals) this is called crosspollination.
Sexual Reproduction
Advantages and Disadvantages of Sexual Reproduction
Sexual Reproduction
Advantages and Disadvantages of Sexual Reproduction
+Offspring show variation
Variation allows species to survive through environmental changes
Gametes must meet
Embryo must be protected and nurtured
