II – Reproduction: A.U sing DNA to Make Proteins: As You grow cells divide producing new cells. These cells become specialized organs and grow larger.

B.Your body is made up of many different proteins proteins. C.Proteins C.Proteins determine your eye color, hair color, bone structure, etc…….

1.Instructions for making proteins are stored in chromosomes which are made up of DNA DNA molecules. 2.DNA 2.DNA consist of two long strands forming a twisted ladder ladder.

a)T he double strands in a molecule are made up of sugars and phosphates. b)N itrogen bases make up the rungs of the ladder.

Bases = ~Adenine ( (( (A) combines with Thymine ( (( (T) ~Guanine ( (( (G) combined with Cytosine ( (( (C) ~The sequence of t tt three b bb bases is a chemical code called a c cc codon. Bases Handle = Sugars & Phosphates Codon

c)The c)The DNA molecule is large, codes for humans are on 46 chromosomes in most cells or 23 pairs.

d)Proteins are made in cytoplasm the nucleus has the instruction for building. The nucleus sends messengers called R RR RNA (ribonucleic acid) a single strand of sugar, phosphates, and bases (DNA is a double strand)

B Making DNA Copies When cells reproduce the D DD DNA must be copied e ee exactly. These copies give each new cell the same instructions as the original cell.

1) 1) DNA Copies DNA DNA molecules separate at the bases. The separated bases pair up with free bases. Now we have two DNA molecules that are identical.

C- Mitosis Mitosis Notes Cell division occurs in a series of stages, stages, or phases. Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) R Resting Stage or Phase INTERPHASE 1 st : INTERPHASE

Mitosis Mitosis begins (cell begins to divide) Centrioles Centrioles (or poles) appear and begin to move move to opposite ends of cell. Spindle Spindle fibers fibers form. 2nd: P PP PROPHASE Centrioles Spindle fibers

3rd: M MM METAPHASE Chromatids (Double chromosomes) attach to the spindle fibers. Chromatids line up in the m mm middle of cell.

Chromatids (Double chromosomes) separate and begin to move to opposite ends of the cell 4th: A AA ANAPHASE

5th: T TT TELOPHASE Two new n nn nuclei form. Chromosomes appear as chromatin (threads-like) M MM Mitosis ends Nuclear membrane

6th: C CC CYTOKINESIS C CC Cell m mm membrane forms around two daughter cells - each with its own n ucleus with identical c cc chromosomes

6th: C CC CYTOKINESIS i ii in Plant C CC Cell Cell membrane forms around two d aughter c cc cells - each with its own nucleus with i ii identical chromosomes. A c cc cell p pp plate forms. cell plate

D- Sexual Sexual Reproduction: Reproduction: Involves the joining of two special reproductive cells, one from each parent. 1- These sex sex cells cells or gametes gametes have half the number of chromosomes as the body cells. 2- Gametes Gametes are formed by a special type of cell division called meiosis.

3- During sexual reproduction the sperm and egg cell join this is called fertilization fertilization. a- a- When they join they form one cell with a complete set of chromosomes.

E-Development E-Development of the Fertilized Egg Egg : A Fertilized egg is called a zygote 1 -Forms new identical cell through the process of mitosis. 2- This process (Differentiation) or cleavage continues forming more and more cells. 3- Sexual reproduction leads to variation in offspring.

F- F- Sexual Reproduction in Plants Plants The flower flower is the reproductive organ in a plant Parts of a Flower a-Stamen a-Stamen = male contains the anther anther which produces pollen grain (male gamete) and the filament filament holds up the anther.

3- 3- Pistil Pistil = female contains the Stigma ~Stigma sticky to catch pollen, style ~style tube leading to ovaries, ovaries ~ovaries which contain ovules the eggs (ovum female gamete) of the flower. o...:"

C.Mitosis: the process by which two nuclei form after cells have doubled chromosomes. 1)Steps of Mitosis: a)Interphase: a)Interphase: Resting Phase. Cytoplasm Cell membrane Nucleolus b)Prophase: b)Prophase: Chromosomes have doubled, spindle fibers have formed, and the nuclear membrane disappears. Double chromosomes Nuclear membrane disappears Spindle fibers form

c)M etaphase: the twin chromosomes line up in the center of the cell on the spindle fibers. Double chromosomes Spindle fibers d)A naphase: the twin chromosomes separate and move away from each other, and move to opposite ends of the cell. The chromosomes are identical. Chromosomes separate

~During anaphase in plants form a new cell wall between the new nucleuses e.Telophase: e.Telophase: Nuclear membrane forms around new chromosomes, cytoplasm pinches in the center. Cytoplasm pinches