Bio Boarding

Unit 2 Review/ Notes

DNA

Draw a nucleotideInclude: Phosphate, Sugar, and Nitrogen base!

What are the building blocks of DNA and RNA?

Nucleotides!!!

What are the four DNA bases?

Adenine ThymineGuanine Cytosine

Which bases pair with which?

What are these base pairings referred to as?

Complimentary base pairs

How many Hydrogen Bonds do A&T have between them? C&G?

A&T = 2 h-bondsC&G = 3 h-bonds

Which bases have stronger Hydrogen bonding between them?

C&G!!!

If DNA is a ladder, what are the sides?

Alternating Sugar and Phosphate molecules!

What are the rungs?

Nitrogen bases!

Which fragment is the smallest?

What does the BRCA gene do?

Regulate cell cycle (it’s a tumor suppressor gene)

What would happen if the BRCA gene was missing?

Increased risk for person to get cancer

An example of a carcinogen is cigarette smoke. Why are carcinogens bad for us?

Carcinogens are chemicals that cause mutations that lead to cancer

Mitosis

Why do we need mitosis? (why do we need our body cells to divide?)

• Growth• Repair damaged cells• Replace old cells

Draw the phases of Mitosis in order!

During prophase, what happens so we can see the DNA?

DNA coils or condenses into chromosomes

What pulls the sister chromatids apart during anaphase?

Spindle fibers!

What would happen if one broke during mitosis?

DNA wouldn’t be evenly distributed between daughter cells…one would have too much one would have too little

What is the longest phase of the cell cycle?

Interphase – where the cell is hanging out and doing its job!

What happens at each checkpoint?G1 checkpoint: Checks for damaged DNA before Synthesis phase (doesn’t want to copy bad DNA!)

G2 checkpoint: (after DNA is copied) Prevents mutated DNA from going into mitosis

Mitosis checkpoint: Checks spindle fibers from metaphase to anaphase. Makes sure the right amount of DNA gets to each cell!

PCR

What is PCR?

Polymerase chain reaction and it’s used to make copies of DNA (like a DNA photocopier)

Think about why we would need to be able to do this…

What is the purpose of the helicase enzyme?

Break H-Bonds to “unzip” the DNA

How would you describe the difference between the DNA in bands A and B?

Gene B is the same as A, but there are more copies of the gene in band B making it show up as a thicker and brighter band!

What are the enzymes that perform DNA replication and what are their roles?

Helicase – breaks hydrogen bonds between base pairs to unzip DNA

DNA Polymerase – adds new nucleotides to a strand of DNA

Ligase – reforms sugar & phosphate backbone