Chapter 4 Genes and DNA

Section 1+2Pages 84-101

What does DNA look like?

• Pieces of the Puzzle: 1. DNA

2. DNA must be able to be

Nucleotides: Subunits of DNA

• A nucleotide consists of a ______, a ______, and a _____. Nucleotides are identical except for their base.

• There are 4 bases: A_____, T_____, G_____, and C______

• All four bases have a different _____.

Chargaff’s Rules

• Guanine and Cytosine always occur in _____ _______ in DNA, as do Adenine and Thymine

Franklin’s Discovery

• Used X Ray diffraction to make images of DNA molecules

• Suggested the ____ shape of DNA

Watson and Crick’s Model

• After seeing Franklin’s image, Watson and Crick concluded that DNA must look like a ____, ______ ______.

• This helped explain how DNA is ______ and how it ______ in the cell.

DNA’s Double Structure

• Double Helix, two sides of the ladder are made of alternating _____ parts and ________ parts.

• The rungs of the ladder are made of a pair of bases:

A______-T______G______-C______

Animated DNA

• http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter3/animation__dna_replication__quiz_1_.html

Making Copies of DNA

• Pairing the bases allows the cell to _______ or make copies of DNA

• The pairs are _____________ since they always pair A-T and G-C

How are copies made?

• During replication, a DNA molecule is _____ ____ the _______, where _____ meet.

• The bases on each side of the molecule are used as a _________ for the new strand.

• As the bases on the original molecule are exposed, _________ ________ are added to each side of the ladder.

• Two DNA molecules are formed.• Half of each of the molecules is

old DNA, half is the new DNA

Unraveling DNA

• DNA is often wound around ______, coiled into strands, and bundled up even more.

• Cell’s without a nucleus the DNA forms ______ ______ within the cell.

• Cell’s with a nucleus the DNA and proteins are bundled into __________.

When are copies made?

• DNA is copied …• The job of ________, ________ and

__________ the DNA is done by proteins within the cell.

Unraveling DNA

• The structure of DNA allows it to hold ________.

• The ______ of the bases is the code that carries the information.

• A gene consists of

• Humans have over ______ genes.

• 2003 Human Genome Project

Unraveling DNA- Quiz

• Where is the DNA in your cells?

• How does so much DNA fit into the nucleus?

• What is the name for strands of DNA wound around proteins?

• When do chromosomes become visible in cells?

• What are chromatids?

• In • It is • C• When the • Two

Genes and Proteins

• DNA code is read like a book, from one end to the other and in one direction.

• Bases form the alphabet of the code.

• Groups of __ bases are code for the ____ _____ profile. (example: AGC)

• A long string of amino acids forms a ______.

• Each gene is

Proteins and Traits

• Proteins are found _______ cells and cause most of the _______ that you see among organisms.

• Proteins act as _______ ________ and ________ for many processes within the cell.

• A single organism may have _______ of genes that code for thousands of proteins.

Help from RNA

• RNA (ribonucleic acid) a molecule

• Helps in the process of

Making of a Protein

• Step 1: A copy is made of one side of the DNA segment where a particular gene is located. This copy is transferred to the _________.

Making of a Protein

• Step 2: This mirror like copy of a DNA segment is called messenger RNA (mRNA).

Messenger RNA..

Making of a Protein

• Step 3: Each group of ____ bases on the mRNA segment codes for ___ amino acid.

Making of a Protein

• Step 4: The mRNA segment is fed through the _______. A ribosome is a cell organelle composed of ____ and _______.

Making of a Protein

• Step 5: Molecules oftransfer RNA (tRNA) deliver amino acids from the cytoplasm to the ribosome.

Transfer RNA (tRNA) transfers

Making of a Protein

• Step 6: The _____ _____

are dropped offat the ribosome.

Making of a Protein

• Step 7: The amino acids are joined to make a ______. Usually, one protein is produced for each _____.

Animated mRNA

• http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_1_.html

How is RNA different from DNA?

• RNA: one strandcontains ______ instead of thymine A, G, C, U

• DNA: two strands A, G, C, T

Changes in Genes• Mutation: a change in the nucleotide-

base sequence of a gene or DNA molecule

• Either __________, ________ or ___________

• Causes an ___________, __________ or _____________

• If the mutation occurs on the sex cells, the mutation can be passed to the _______ _________

• Mutations happen _______ • Mutagens are any physical or chemical

agent that can cause the mutation (examples: UV radiation, X rays, cigarette smoke)

• Examples are

Example of Substitution

• Sickle Cell Anemia- affects red blood cells. When _______ is substituted for _______ _______ in a blood protein. The change in shape isn’t good for the cell to carry oxygen and clot in vessel (very painful).

Genetics

• Genetic Engineering: Manipulate individual genes to create new products, such as foods, drug or fabrics

• Genetic Identification: DNA is your unique fingerprint, only identical twins share DNA

Clone:

Selective breeding: A technique to produce offspring with desirable traits. Inbreeding:

Hybridization:

Web sites…..• DNA and Genetics:• http://www.pbs.org/wnet/dna/episode1/index.html#• http://www.pbs.org/wgbh/aso/tryit/dna/• http://learn.genetics.utah.edu/content/begin/dna/• http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html• http://www.mesacc.edu/~tinhw34501/psquare.pdf• http://www.nature.ca/genome/05/051/0511/0511_m205_e.cfm• http://www.pbs.org/wgbh/nova/body/sequence-DNA-for-yourself.html• http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html • Genetics:• http://pbskids.org/dragonflytv/games/game_dogbreeding.html• http://www.worldwildlife.org/sites/inner-animal/index.html• http://anthro.palomar.edu/mendel/mendel_2.htm• http://www.athro.com/evo/gen/punexam.html• http://www2.edc.org/weblabs/Punnett/punnettsquares.html• http://biology.clc.uc.edu/courses/bio105/geneprob.htm• http://www.cellsproject.org/examples/sc/page23.html• http://glencoe.mcgraw-hill.com/sites/0078778066/student_view0/chapter5/math_practice.html• http://anthro.palomar.edu/mendel/mendel_1.htm• http://www.biology.arizona.edu/Mendelian_genetics/mendelian_genetics.html• http://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel1.htm• http://www.pbs.org/wgbh/nova/body/cracking-the-code-of-life.html