Biology Slide 1 of 21 Copyright Pearson Prentice

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Biology Slide 1 of 21 Copyright Pearson Prentice Hall End Show

Biology Slide 1 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication 12 -2 Chromosomes and DNA Replication Slide 2

12– 2 Chromosomes and DNA Replication 12 -2 Chromosomes and DNA Replication Slide 2 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication DNA and Chromosomes In prokaryotic cells, DNA is

12– 2 Chromosomes and DNA Replication DNA and Chromosomes In prokaryotic cells, DNA is located in the cytoplasm. Most prokaryotes have a single DNA molecule containing nearly all of the cell’s genetic information. Slide 3 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Chromosome E. Coli Bacterium Bases

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Chromosome E. Coli Bacterium Bases on the Chromosomes Slide 4 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Many eukaryotes have 1000 times

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Many eukaryotes have 1000 times the amount of DNA as prokaryotes. Eukaryotic DNA is located in the cell nucleus inside chromosomes. The number of chromosomes varies widely from one species to the next. Slide 5 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Chromosome Structure Eukaryotic chromosomes contain

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Chromosome Structure Eukaryotic chromosomes contain DNA and protein, tightly packed together to form chromatin. Chromatin consists of DNA tightly coiled around proteins called histones. DNA and histone molecules form nucleosomes. Nucleosomes pack together, forming a thick fiber. Slide 6 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Eukaryotic Chromosome Structure Chromosome Nucleosome

12– 2 Chromosomes and DNA Replication DNA and Chromosomes Eukaryotic Chromosome Structure Chromosome Nucleosome DNA double helix Coils Supercoils Histones Slide 7 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication What happens during DNA replication? Slide 8 of

12– 2 Chromosomes and DNA Replication What happens during DNA replication? Slide 8 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication Each strand of the DNA double helix has

12– 2 Chromosomes and DNA Replication Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing. In most prokaryotes, DNA replication begins at a single point and continues in two directions. Slide 9 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication In eukaryotic chromosomes, DNA replication occurs at hundreds

12– 2 Chromosomes and DNA Replication In eukaryotic chromosomes, DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied. The sites where separation and replication occur are called replication forks. Slide 10 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication Duplicating DNA Before a cell divides, it duplicates

12– 2 Chromosomes and DNA Replication Duplicating DNA Before a cell divides, it duplicates its DNA in a process called replication. Replication ensures that each resulting cell will have a complete set of DNA. Slide 11 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication During DNA replication, the DNA molecule separates into

12– 2 Chromosomes and DNA Replication During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template for the new strand. Slide 12 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication New Strand Original strand Nitrogen Bases Growth Replication

12– 2 Chromosomes and DNA Replication New Strand Original strand Nitrogen Bases Growth Replication Fork DNA Polymerase Copyright Pearson Prentice Hall Slide 13 of 21 End Show

12– 2 Chromosomes and DNA Replication How Replication Occurs DNA replication is carried out

12– 2 Chromosomes and DNA Replication How Replication Occurs DNA replication is carried out by enzymes that “unzip” a molecule of DNA. Hydrogen bonds between base pairs are broken and the two strands of DNA unwind. Slide 14 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Chromosomes and DNA Replication The principal enzyme involved in DNA replication is

12– 2 Chromosomes and DNA Replication The principal enzyme involved in DNA replication is DNA polymerase joins individual nucleotides to produce a DNA molecule and then “proofreads” each new DNA strand. Slide 15 of 21 Copyright Pearson Prentice Hall End Show

12– 2 Click to Launch: Continue to: - or - Slide 16 of 21

12– 2 Click to Launch: Continue to: - or - Slide 16 of 21 End Show Copyright Pearson Prentice Hall

12– 2 In prokaryotic cells, DNA is found in the a. cytoplasm. b. nucleus.

12– 2 In prokaryotic cells, DNA is found in the a. cytoplasm. b. nucleus. c. ribosome. d. cell membrane. Slide 17 of 21 End Show Copyright Pearson Prentice Hall

12– 2 The first step in DNA replication is a. producing two new strands.

12– 2 The first step in DNA replication is a. producing two new strands. b. separating the strands. c. producing DNA polymerase. d. correctly pairing bases. Slide 18 of 21 End Show Copyright Pearson Prentice Hall

12– 2 A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand.

12– 2 A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand. What is the base sequence on the other strand? a. GCGAATTCG b. CGCTTAAGC c. TATCCGGAT d. GATGGCCAG Slide 19 of 21 End Show Copyright Pearson Prentice Hall

12– 2 In addition to carrying out the replication of DNA, the enzyme DNA

12– 2 In addition to carrying out the replication of DNA, the enzyme DNA polymerase also functions to a. unzip the DNA molecule. b. regulate the time copying occurs in the cell cycle. c. “proofread” the new copies to minimize the number of mistakes. d. wrap the new strands onto histone proteins. Slide 20 of 21 End Show Copyright Pearson Prentice Hall

12– 2 The structure that may play a role in regulating how genes are

12– 2 The structure that may play a role in regulating how genes are “read” to make a protein is the a. coil. b. histone. c. nucleosome. d. chromatin. Slide 21 of 21 End Show Copyright Pearson Prentice Hall

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