Chapter 12 Section 1 Notes
DNA
Biology Pgs. 263-266
Name:
Objectives
_________________the relationship between genes and DNA
______________the overall structure of the DNA molecule
Scientists discovered that the _______________________stores and transmits the genetic
information from one generation of an organism to the next.
Bacteriophages
A virus that infects bacteria is known as a____________________.
Bacteriophages are composed of a DNA or RNA core and a protein coat.
When a bacteriophage enters a bacterium, the virus attaches to the surface of the cell and
_________________information into it.
The viral genes produce many new bacteriophages, which eventually destroy the bacterium.
When the cell splits open, hundreds of _______________________burst out.
The Components and Structure of DNA
DNA is made up of____________________.
A nucleotide is a monomer of nucleic acids made up of a five-carbon sugar called deoxyribose, a
phosphate group, and a nitrogenous base.
The backbone of a DNA chain is formed by _____________and phosphate groups of each
nucleotide.
The nucleotides can be joined together in any order.
Chapter 12 Section 2 Notes
Chromosomes and DNA Replication
Biology pgs. 267-269
Objectives
____________________the events of DNA replication
_____________the DNA molecule to chromosome structure
In prokaryotic cells, DNA is located in the____________________.
Most prokaryotes have a single DNA molecule containing nearly all of the cell’s genetic information.
Chromosome Structure
Eukaryotic chromosomes contain DNA and protein, tightly packed together to
form_________________.
Chromatin consists of DNA tightly coiled around proteins called______________.
DNA and Chromosomes
Eukaryotic Chromosome Structure
DNA Replication
Each strand of the DNA double helix has all the information needed to reconstruct the
other half by the mechanism of_______________
The sites where separation and replication occur are called replication forks.
Before a cell divides, it duplicates its DNA in a process called____________________.
Replication ensures that each resulting cell will have a complete set of DNA
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 ____________________for the new strand.
How Replication Occurs
DNA replication is carried out by enzymes that _____________a molecule of DNA.
Hydrogen bonds between base pairs are broken and the two strands of
DNA___________
The principal enzyme involved in DNA replication is DNA polymerase.
DNA polymerase joins individual nucleotides to produce a DNA molecule and then “proofreads” each
new DNA strand.
Chapter 12 Section 3 Notes
RNA and Protein Synthesis
Biology pgs. 300-306
Objectives
____________how RNA differs from DNA
________________transcription and the editing of RNA
______________the Genetic Code
________________translation
______________the relationship between genes and proteins
______________are coded DNA instructions that control the production of proteins.
The Structure of____________
RNA consists of a long chain of nucleotides.
There are ___________main differences between RNA and DNA:
The ____________in RNA is ribose instead of deoxyribose.
RNA is generally ____________-stranded.
RNA contains ____________in place of thymine.
Types of RNA
There are __________________of RNA:
messenger RNA
ribosomal RNA
transfer RNA
Transcription
RNA molecules are produced by copying part of a nucleotide sequence of DNA This process is
called____________________
Transcription requires the enzyme RNA polymerase.
RNA polymerase binds only to regions of DNA known as promoters.
Promoters are signals in DNA that indicate to the enzyme where to bind to_________________.
RNA Editing
When RNA molecules are formed, introns and ____________are copied from DNA.
The Genetic Code
The genetic code is the “language” of mRNA instructions.
The code is written using ____________“letters” (the bases: A, U, C, and G).
A _________________consists of three consecutive nucleotides on mRNA that specify a particular
amino acid.
Each codon specifies a particular _______________that is to be placed on the
polypeptide chain.
Some amino acids can be specified by more than one codon.
Translation
______________________takes place on ribosomes.
During translation, the cell uses information from messenger RNA to produce proteins.
The Roles of RNA and DNA
The cell uses the DNA “master plan” to prepare RNA “blueprints.” The DNA _____________in the
nucleus.
The RNA molecules go to the protein building sites in the cytoplasm—the__________________
Genes and Proteins
Genes contain instructions for assembling__________________
Chapter 12 Section 4 Notes
Mutations
Biology pgs. 307-308
Objectives
___________gene mutations and chromosomal mutations
Kinds of Mutations
________________are changes in the genetic material.
Mutations that produce changes in a single gene are known as gene mutations.
Mutations that produce changes in whole chromosomes are known as ________________mutations.
Point mutations include substitutions, insertions, and deletions.
______________usually affect no more than a single amino acid.
The effects of insertions or deletions are more______________.
The addition or deletion of a nucleotide causes a shift in the grouping of codons.
Changes like these are called_____________________
In an______________, an extra base is inserted into a base sequence.
In a____________, the loss of a single base is deleted and the reading frame is shifted.
Chromosomal Mutations
Chromosomal mutations involve changes in the _________________or structure of chromosomes.
Chromosomal mutations include deletions, duplications, inversions, and translocations.
Significance of Mutations
Many mutations have ___________________effect on gene expression.
Some mutations are the cause of_________________________
Chapter 12 Section 5 Notes
Gene Regulation
Biology pgs. 309-312
Objectives
___________________a typical gene
__________________how lac genes are turned off and on
_________________how most eukaryotic genes are controlled
________________gene regulation to development
An _____________is a group of genes that operate together.
In E. coli, these genes must be turned on so the bacterium can use lactose as food.
Therefore, they are called the lac operon.
The lac genes are turned off by repressors and turned on by the presence of lactose.
Many genes are regulated by repressor proteins.
Some genes use ________________that speed transcription.
Sometimes regulation occurs at the level of protein synthesis.
Eukaryotic Gene Regulation
Operons are generally ______________in eukaryotes.
Most eukaryotic genes are controlled individually and have regulatory sequences that are much more
complex than those of the lac operon.
Development and Differentiation
As cells grow and divide, they undergo_________________, meaning they become
specialized in structure and function.
__________________control the differentiation of cells and tissues in the embryo.