Bell work 10-27

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Copyright© 2015 EducAide Software Inc. All rights reserved.

Reminders Test corrections during AST, before or after school End of three weeks is TOMMORROW Cell cycle and DNA test 11-6 counted

Quiz about DNA

Today in class describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication Talk about how DNA is replicated

Review about DNA

What is the structure below called?

What are the three pieces that make up a nucleotide? Phosphate Nitrogen Base Sugar

What kinds of bonds exists between the Bases of DNA?

Watson and Crick found that DNA was in the shape of an?

Adenine always binds with______ Cytosine always binds with_____ Thymine always binds with_____ Guanine always binds with_____

Gerenal Chrmosomes DNA: Directs cell activity Gene: a segment of DNA that transmits information. Chromosome: a single DNA molecule and its associated proteins. Chromatid: copy of a chromosome.

Chromosomes Eukaryotes Prokaryotes Found in the nucleus DNA is found in the cytoplasm (nucleiod region) Single circular DNA molecules DNA replication begins at a single point in the chromosome & proceeds in both directions until the chromosome is replicated Eukaryotes Found in the nucleus Chromosome number varies between species DNA replication occurs at hundreds of places called replication forks

Chromosomes How much DNA in a human nucleus? What is chromatin? more than 1 meter What is chromatin? DNA tightly coiled around proteins called histones

Chromosomes How are chromosomes constructed? DNA & histones form beadlike structures called nucleosomes Nucleosomes pack with one another to form thick fibers Fibers are shortened by a system of loops & coils

Replication

Replication – General Info The exact copying of DNA Replication occurs in both directions DNA must be copied before cells divide  each daughter cell has a complete set of DNA Original strands serve as templates for new strands

Replication – General Info How it happens: Helicase (enzyme) unwinds the DNA by breaking hydrogen bonds

Replication – General Info DNA polymerase (enzyme) joins individual nucleotides to each separated strand, producing DNA molecule DNA polymerase also proofreads each new DNA strand to make perfect copies

Replication – General Info Results: 2 DNA molecules  each contains one original strand & one new strand

Sometime a MUTATION can occur Changes in DNA that affect genetic information

What Causes Mutations? There are two ways in which DNA can become mutated: Mutations can be inherited. Parent to child Mutations can be acquired. Environmental damage Mistakes when DNA is copied

How are they inherited Only mutations to the gametes (egg and sperm cells) can be passed on to offspring. Mutations in body cells only affect the organism in which they occur. They cannot be passed on to offspring.

Significance of Mutations Most are neutral Eye color Birth marks Some are harmful Sickle Cell Anemia Down Syndrome Some are beneficial Sickle Cell Anemia to Malaria Immunity to HIV

DNA Cut and Paste Directions: 1. Cut out the following shapes. 2. Fold the color of paper that corresponds to the shape that you are cutting so that you do not have to cut so many (4 at time is good). 3. The following are the color combinations for the shapes Yellow – 4 A shapes – write A on both side of the paper Green – 4 G shapes – write G on both sides Blue – 4 T shapes – write T on both sides Orange – 4 C shapes – write C on both sides White – 16 S shapes – write S on both sides Black – 16 P shapes – write P on both sides 4. You are now going assemble 16 individual nucleotides, matching the dots (*) to dots and pluses (+) to pluses. Use glue to hold the nucleotides together.

Table of Contents Pre-AP only Root words page 74 Cell Cycle notes page 75-76 DNA notes page 77 DNA Double Helix Activity 78-79 DNA Cut and Paste paper 80 Bell work page 81 DNA Replication 82-83