DNA Structure Analysis Questions Answered

1. The twisted ladder structure of DNA is called a Double Helix.

2. The backbone of DNA is made up of deoxyribose sugar and phosphate group.

3. The ladder-like rungs of DNA are made up of nitrogenous bases.

4. Adenine always pairs up with Thymine.

5. Cytosine always pairs up with Guanine.

6. A nucleotide is the basic building block of DNA. A nucleotide is made up of one deoxyribose sugar, one phosphate group, and one nitrogenous base.

DNA Replication

p. 46

DNA Packaging

• A cell’s nucleus contains chromosomes made up of DNA.

Chromatin Fibers

Each chromatin fiber is a tightly wound supercoil

Each super coil is made up of coils. A coil is a chain of beadlike structures called nucleosomes

Each nucleosome consists of DNA wound around histones

DNA replication

• Before a cell divides, it duplicates its DNA in a copying process called replication

• this process insures that each resulting cell receives a complete set of DNA molecules

• During 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 a new strand

DNA Replication• In Eukaryotic Cells

replication occurs in hundreds of places at once

• Replication proceeds in both directions until each chromosome is completely copied

• The places where separation and replication occur are called replication forks

Creating a New Strand

• Two strands of the double helix separate allowing two replication forks to form

• Each new strand forms following the rules of base pairing. For example:

The original strand has the bases: TACGTT

What would the complementary strand be?

ATGCAA

• The result is two DNA molecules identical to each other and to the original

• NOTE: each DNA molecule will have one original strand and one new strand.

• More practice. Create the complementary strand

CCGTACTTACG

Answer

GGCATGAATGC

How Replication Occurs

• DNA replication is carried out by a series of Enzymes

• The enzymes “unzip” a molecule of DNA by breaking the hydrogen bonds between the base pairs

• DNA polymerase joins individual nucleotides to produce a DNA molecule and proofreads each new DNA strand

Placed on the same page as your notes

Glue the picture of DNA replication into your notes. Copy diagram 1 into your notes. The diagram shows one side of a strand of DNA. Create the complementary strand of DNA that would be made by the process of replication.

A

T

G

A

C

G

A

C

T

Diagram 1

On page 45 of your spiral…Word Definition in own words Picture

Double Helix

Nucleotide

Nitrogen Base

Replication

Transcription

Codon

Translation

Anticodon

Ribosome

Amino Acid

Protein