Reproduction and Genetics Notes

 

The purpose of reproduction is simple...

 

SURVIVAL OF THE SPECIES

 

Two ways of survival:

• number of offspring
• care of offspring

 

In general,

If you choose to not care for the offspring, the smaller chance they will survive, so you need to give birth to more. If you choose to care for the offspring, the lower you should give birth to.

 

Polar Bears

Let's say that we are polar bears and there is only a couple of us alive in the whole world. Our goal is that we can have 3 kids so we can keep our kind alive. We can go two ways, you can have 8 kids and not care for them as much and still have 3 that are alive in the end or we can have 3 kids and take care of them more and then still most likely then only 3 would live.

 

Our human species is dying out slowly. Most parents are only giving birth to about 1 child, which leaves a less number of people to reproduce. We need to increase this number in order to stop our human species from dying out.

 

 

Two kinds of reproduction:

 

Asexual Reproduction-a single parent has offspring that are genetically identical to the parent.

 

Sexual Reproduction-offspring formed by the combination of genetic material from two parents. All mammals go through sexual reproduction.

 

  

Methods of Asexual Reproduction

 

• Budding-part of parents pinches off to form new organism (there will be pictures)
• Organisms that bud: Hydra (not the mythological one)

• Fragmentation- parts of one organism break off and grow to form a new organism

• Organisms that fragment: Planaria, Sea Star, Sea Cucumber,

• Regeneration-one organism loses a body part which is able to grow into an entirely new organism                                        Joy was here!!! =p

 

 

2-26-09 By: Josie!!!:) 2nd Core

Sexual Reproduction 

Sexual reproduction is characterized by the difference between male and female

Sex cells:

~Male-sperm

~Female-egg

Combining sperm and egg is known as fertilization

 

Fertilization

When fertilization occurs the resulting cell is known as a zygote

After fertilization the zygote's cells divide and grow

After about 12 days the zygote has enough cells to be known as an embryo

 

Right here,we talked about fertility clinics and stem cell research. "Extra" eggs are kept in fertility freezers waiting for someone to want them. When chances are slim that their parents will have more children, some people want to do stem cell research on these embryos. What do you think?

 

Basic Genetics

Humans have a total of 46 chromosomes (23 pairs)

A chromosome is a section of DNA that carries genetic information

Each individual sperm and egg has only 23 chromosomes (then they combine, which makes 46!)

There is a VERY RARE CHANCE that you will have more chromosomes from one parent than the other

 

Sexual Reproduction

The main difference between sexual, and asexual, is genes. Asexual creates geneticaly identical offspring.

 

The males create sperm to fertelize the egg, (When the sperm combines with the egg.) while the women create the egg. Whether or not the female carries the egg does not matter, the first two facts are constants. 

 

A fertilized egg is also called a zygote.

 

Once the zygote is fertilized, it divides into a much larger orgaanism.

 

If the zygote splits in half while dividing, they become identical twins