Good Morning! Thanks for getting started on:

• Please get out your homework LT 16 and vocab for a stamp

• Start drawing a DNA molecule on your whiteboard

• Warm-Up: On your whiteboard, draw a DNA molecule and discuss with your group

–Label:

1. Double Helix

2. The Base Pairs

3. Nucleotides

Monday, February 23, 2015

Activity/Assignment

1. Warm-up: on your whiteboard, draw a DNA molecule

2. Recap DNA structure

3. DNA replication lecture/whiteboard activity

4. Finish POGIL

*If you haven’t taken the Quiz, today is the last day to do so

Learning Objectives • Students will be able to

identify and describe the structure of DNA

• Students will be able to describe how the structure of a DNA molecule allows for it to replicate itself accurately: T only bonds to A and G only bonds to C

• Students will be able to describe when, why, and how DNA replicates

List the 3 biomolecules we learned and their subunits

DNA Structure

• 4th biomolecule: nucleic acids

– Subunits are called nucleotides

• Examples: DNA and RNA

How do we digest large biomolecules like the carbohydrates that are in

bread or pasta or the protein in meat?

How do we digest large biomolecules, like the carbohydrates that are in

bread or pasta or the protein in meat?

• Carbs get broken down by amylase in the mouth (saliva/spit) and the stomach/small intestine into monosaccharides

• Monosaccharides can now diffuse into the blood stream

Nucleotides

4 Base Pairs

• Purines:

–Adenine and Guanine

• Pyrimidines:

– Thymine and Cytosine

Why does A only bond to T and C only bond to G?

Where do we get nucleotides to make new copies of our DNA?

So, to answer August’s question in the parking lot….

Why do cells divide?

Why do cells divide?

1. To grow

2. To repair damaged cells

3. To replace old, dead cells

When does DNA replicate?

Question 2: When does DNA replicate?

• During the S Phase of the cell cycle

Why does DNA replicate?

Why does DNA replicate?

• Every time a cell divides, the resulting daughter cells must contain the exact same DNA as the parent cell

• DNA Replication:

• https://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related

• Chromosome Wrapping: https://www.youtube.com/watch?v=yqESR7E4b_8

How does DNA replicate? • To accomplish DNA replication, each strand of

existing DNA acts as a template for replication

DNA Replication

DNA Replication

Replication = DNA copies itself exactly

(occurs within the nucleus)

Happens during the S phase of the cell cycle

Any mistake in copying = mutation

DNA mutation = chromosomal mutation

Chromosomes contain genes and genes are segments of DNA

Part 1: Basic Facts of DNA Replication

Complementary base pairing makes replication possible

C - G

A - T

Part 1: Basic Facts of DNA Replication

One side of a DNA molecule is a template for making the other side (strand)

Check for Understanding: How is one side of a DNA molecule a template for making a new and

exact copy of itself?

The Enzymes

1. Helicase: unzips the double strand by breaking hydrogen bonds

2. DNA Polymerase: adds bases to the new strand in the complementary form

Part 2: The Process of DNA Replication

1. Uncoil & unzip DNA molecule

Enzyme (Helicase) breaks

weak Hydrogen Bond

between bases

Part 2: Process of DNA Replication

2. Polymerase brings in complementary N-bases

DNA Replicase

Check for engagement: What are the main two enzymes

involved in DNA replication? What are their jobs?

What are the main two enzymes involved in DNA replication? What are their jobs?

Here you have DNA replication!

C - G

A - T

Semi-conservative replication

Each new DNA molecule contains

one old strand

&

one new strand

- How does the structure of DNA allow for it to make an accurate copy of itself? - What would happen if something went wrong?

DNA vs. RNA

DNA RNA

Sugar = deoxyribose Sugar = ribose

Double-stranded

molecule

Single-stranded

molecule

Thymine bonds with

adenine

Uracil instead of thymine

DNA vs. RNA

DNA RNA

Nuclear DNA

Mitochondrial DNA

Chloroplast DNA

mRNA = messenger

tRNA = transfer

rRNA = ribosomal

Nuclear DNA never

leaves the nucleus

Assembled in nucleus,

moves to cytoplasm

(leaves the nucleus)

RNA vs. DNA