Genes & Red Blood Cells

Genes is a section in a DNA strand that holds the instructions for a specific function.

The Book of Brenda 

1. A chapter - which are chromosomes, You get 23 pairs from each parent so in total you have 46. 

2. A paragraph- which are Genes, you have 20,000 - 30,000 genes in your body!

3. Sentences- Which is like gene splicing, the TRNA and the MRNA

2. Words- which are the codons that make up the DNA

1. Letters- there are 4 of them , A & T, C & G or in RNA there is A & U, C & G. there is a six one 

• We have about 30,000 genes in our whole body

• Blood Cells are the only cells that dont carry DNA because they dont have nuclei.

• The reason they have no nuclei is because they have a specific biconcave shape, and a nucleaus would not let it have that. They have that shape because it allows them to have a bigger surface area

• The part of the body that uses the most oxygen is the brain & the nucleus is the brain of the cell, so if it has a nucleus the oxygen that needs to be carried is going to be used up by the nucleus instead of being tranfered around the body.

Link:

http://www.science.edu.sg/ssc/detailed.jsp?artid=6140&type=6&root=4&parent=4&cat=48

What is Science

Biology is a philosophy.

Philosophy is a way of thinking.

Science is all about posing & answering questions.

Science does not involve supernatural or religious believes. 

Its all based on facts & experiments

There are many theories in biology.  For example:

-The Cell Theory -  Cells can be made from only pre-existing cells

-The Big Bang Theory- That a big explosion started life on Earth.

A theory are a bunch of facts & well tested experiments. You need a lot of facts to make a theory.

What is Life?

What do you classify as being living?

Is a virus living?

Why not? it reproduces, & gets energy right?

In order to be considered living you need to be able to get energy & reproduce.

There are 2 theories. 

The most commonly known is the CELL THEORY. 

In the CELL THEORY it says that all living cells come from other pre-existing cells & that all living things are composed of cells.

Another theory is the STAR STUFF theory in which all living things come from things brought from outer space.                                                                                                                                          

They are all also made of organic compounds.

There are 4 organic compounds---

1. Lipids- store energy
   
2. Carbs- are the main source of energy
   
3. Nucleic Acids- contain genetic information needed to reproduce and get energy
   
4. Proteins- help produce enzymes to speed up chemical reactions in your body.

The WATER Molecule

• is held together by hydrogen bonds
• cohesion is the attraction between substances
• adhesion is the attraction between different substances
• A mixture is made of 2 elements or more
• A solution is an even distribution of substances in a mixture
• A suspension is non dissolved, not even distrubution of substances in a mixture

Chemical Bonds

• There are 2 types of bonds
  

1. Covelant bonds- share atoms to form molecules- molecules are the smallest units in compounds.- 
2. ionic bonds- share ions that can be (+) or (-) charged. its (-) when it adds an electron and when it looses one it becomes (+)

Elements

• there are over 180 elements known
• 92 of them are natural

Chemical Reactions

• Enzymes are proteins used to speed up chemical reactions.
• They are specific to the reaction they can speed up. 

Reproduction

• All that living things do is get energy & reproduce.

• The two types of reproduction are asexual & sexual reproduction.

It all starts by the splitting of DNA by fertilization.

Fertilization!!!

• Sexual Reproduction:
  

A sperm cell enters the egg. When it does the tail falls off and the head explodes letting out the Male DNA. 

Meiosis

Think of meiosis as making a MINI me.  In this process a single diploid cell, is divided into 4 different haploid cells. 

Meiosis insures variety because of two things. During prophase the tetrads cross-over. When they cross over, they exchange some genetic material. 

Then in meiosis II, they separate into 4 completely different cells. Not one containing the same information.

ASEXUAL REPRODUCTION!

During asexual reproduction, MITOSIS takes place.

During mitosis, a single cell divides into 2 cells in 6 stages.

Prophase, metaphase, anaphase, telophase, cytokinesis, and interphase.

Chromosomes line up in a straight line in the middle of the cell and then are pulled apart by spindles.

So whats the difference??

How is DNA Replicated?

The Female & Male DNA are unzipped by enzymes, then re-zipped almost immediately. 

DNA is made of 4 substances & is based on complementary base pairing meaning that the bases will always be paired with the same different base. A is always with T & C is always paired with G. That way when its easy for the cell to put the DNA together. They are held together by weak hydrogen bonds, which is where the enzymes break apart the DNA.

The Female & the male both have 23 chromosomes.  meaning the offspring will have 46 chromosomes. 

DNA

NOT DONE!!!