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Chapter 4 Review. ANSWERS
Use with textbook pages 123-129.
Inside the nucleus
Vocabulary
23
46
Genes
Number
type
Nucleolus
Nucleus
Genetic
Proteins
DNA
Chromosomes
Molecule
Ribosomes
Use the terms in the vocabulary box to fill in the blanks. Each term may be used more than once. You
will not need to use every term.
1. The DNA(inside the nucleus) directs and controls the ability of the cell to grow, develop, and
replicate (make copies of itself).
2. The instructions for how to carry out all cell activities are carried in DNA
, which is a
long, two-stranded Molecule (chemical!)
.
3.
DNA
stores instructions for everything that the cell does. It stores genetic
material – information that is passed on from one generation to another when organisms
reproduce.
4. Strands of DNA are packaged tightly into structures called
chromosomes
.
5. Each type of organism has a specific
number
of chromosomes.
6. Humans have 46
chromosomes that are arranged in 23 pairs.
7.
Genes
are small segments of DNA that carry instructions for making
proteins. They are found at specific places on the DNA (chromosomes)
.
8. Proteins are a type of
molecule
that all the cells of the body need in order to
work properly.
9. Proteins are made in the cell by
ribosomes
, which are the made by a large
structure in the nucleus called the nucleolus
.
The Control Center of the Cell
Use with Textbook pages 125-130
Use the diagram to the right to help you answer question 1.
1. Describe the structure of DNA.
DNA is two long chains of nucleotides that are
connected together at the nitrogenous bases in a spiraling shape called a double
helix. It looks like a twisted ladder.
2. What is this structure called?
A double
helix .
3. What are the sides of this molecule (they look a bit like ribbons that are curling) made
of?
Deoxyribose
And phosphate
.
4. What are the inside “rungs” of this “twisted ladder” structure made of?
Nitrogenous bases
.
5. What are the names of the building blocks of this molecule?
nucleotides
6. What are the names of the four different building blocks (above)?
Adenine, thymine, guanine and cytosine
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Fill in the blanks with the correct terms. Then use your answers to question 7-11 to label the
diagram below.
7. The organelle that contains the DNA of the cell:
nucleus
8. The chemical (molecule) containing
instructions for everything the cell does:
DNA
9. Tightly packed structures of DNA found during
cell division:
Chromosomes
10. Disorganized (looking) form of DNA found
when the cell is NOT dividing:
chromatin
11. Section of the DNA molecule that contains the
information to make a protein:
gene
Look at the inside of the nucleus of the cell in the
diagram. What must this cell be just about to do? It
must be about to divide since we can see that
chromosomes have formed. You will only see
chromosomes in a cell if it is going to enter cell
division. (otherwise, you would just see a messy
looking chromatin in there)
What is the name given to a complete set of genes for
an individual?
A genome.
True or False?
Use with textbook pages 131-132.
Read the statements given below. If the statement is true, write “T” on the line in front of the
statement. If it is false, write “F” and rewrite the statement to make it true.
#
T or
F?
1.
F
Correct Statement?:
2.
T
Correct Statement?:
3.
T
Statement
The nucleolus directs and controls all of the cell’s activities.
The information contained in the nucleus controls all of the cell’s activities.
(the nucleolus makes ribosome subunits. )
Instructions for how to carry out all cell activities are carried in molecules of
DNA.
N/A
Correct Statement?:
DNA stores information that is passed on from one generation to another when
organisms reproduce.
N/A
4.
F
Correct Statement?:
Humans have 46 pairs of chromosomes
Humans have 23 pairs of chromosomes, making 46 TOTAL in each cell.
3
5.
F
Correct Statement?:
6.
T
Correct Statement?:
7.
T
Correct Statement?:
8.
F
Correct Statement?:
One pair of ribosomes helps determine if a person will be born as a male or
female.
One pair of chromosomes (the 23rd pair called X and Y) will help determine
if a person will be born a male or a female.
The nucleolus makes ribosomes
The nucleolus makes the subunits of the ribosomes that will assemble in the
cytoplasm when they attach to a mRNA strand at the start codon.
Ribosomes make proteins
Genes make chromosomes.
Genes are sections of DNA that code for one protein. They are found
contained in the chromosomes.
Use with textbook pages 121-132.
The function of the nucleus within the cell.
Match each term of the left with the best Descriptor on the right. Each Descriptor may be used
only once.
Term
Descriptor
Chromosome
G
A. Segment of DNA located at a specific place on a chromosome
DNA
(B)+C
B. Controls all the activities within a cell
Gene
A
C. A molecule found in the cell nucleus that carries genetic
information
Nucleolus
F
D. essential molecules needed to carry out cell activities
Nucleus
B
E. makes proteins
Proteins
C
F. Makes ribosomes
G. tightly packed structure of DNA
Circle the letter of the best answer.
1. Proteins are made by
a. The ribosomes
b. chromosomes
c. DNA
2. Approximately how many proteins are in the human body?
a. 100 b. 1 000
c. 10 000
d. 100 000
3. Which of the following are functions of proteins?
I.
Carry out cell functions
II.
Form parts of cell structures
III.
Control all of the cells functions
a. I and II only
b. I and III only
c. II and III only
d. I, II and III
4. What instructions do genes carry?
a. To make proteins
b. To make mitochondria
c. To make chloroplasts
d. To make endoplasmic reticulum.
d. the nucleolus
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5. How many chromosomes do humans have?
a. Chromosomes are too small to be counted
b. Between 90 000 and 100 000
c. 92 arranged in 46 pairs
d. 46 arranged in 23 pairs
6. Which of the following best describes DNA?
I.
Twisted in a spiral shape
II.
Shaped like a ladder
III.
Long, two-stranded molecule
a. I and II only
b. I and III only
c. II and III only
d. I, II, and III
Use with textbook pages 136-141.
Mutations concept map. Complete the following concept map about genetic mutations.
4.2. GENE MUTATION
Answer the questions below.
use with textbook pages 136-143
1. What is a gene mutation?
Any change in the sequence of the nitrogenous
bases of a gene (a section of the DNA molecule)
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2. Give the three types of gene mutations. Positive, negative and neutral (caused
by additions, deletions or substitutions)
3. What type of mutation is beneficial to an organism? Positive
4. Give one example of a negative mutation. From the book: Sickle cell anemia. THE
mutation is in the gene for the protein called hemoglobin. The mutation causes
Hb to “sickle” – it makes the shape of a “C” causing the blood cell to have take
that shape as well so that it can’t carry oxygen properly.
5. What type of mutation appears to have no effect on an organism? neutral
6. What are mutagens?
Any agent that can cause mutations in DNA
7. Give four examples of environmental mutagens.
Viruses, uv radiation, x-rays,
pesticides, herbicides, cigarette smoke, mercury, heavy metals, ketchup, peanut
butter, etc.
8. What are researchers doing to the mutated gene when they use gene therapy?
They are REPLACING the mutated gene with a normal functioning gene.
The normal functioning gene should “cure” the disease if the disease is caused
by an mutation!
The Effects of Mutations
Vocabulary.
DNA
Gene therapy
Mutagens
Negative mutations
Organism
Proteins
use with textbook pages 138-143
Gene mutation
Healthy gene
Mutated gene
Neutral mutations
Positive mutations
Use the terms in the vocabulary box to fill in the blanks. You will not need to use every term. You
may use terms more than once.
1. A
gene mutation
is a change in the genetic material of a gene.
2. Changes to DNA may cause proteins
to be made incorrectly
or with an incorrect shape.
3. Factors in the environment, called mutagens
can cause mutations.
4. Radiation, cigarette smoke, and pesticides are examples of
mutagens .
5. Mutations that are harmful to an organism are called
Negative .
6. Mutations that are helpful to an organism are called
Positive
. For
instance, some plants carry a mutated gene that protects them from disease.
7. Mutations that have no effect on an organism are called
Neutral
.
8. New techniques for treating gene mutations are called
gene therapy
and
may involve replacing a
Mutated gene
with a
healthy gene
.
Match each term of the left with the best Descriptor on the right. Each Descriptor may be used
only once.
Term
Descriptor
Gene mutation
D
A. techniques developed to replace mutated genes
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Gene therapy
Mutagens
Negative
mutations
Neutral mutation
Positive mutation
A
G
C
B. a mutation that does not affect the organism
C. a mutation that harms an organism
D. a change in the genetic material
B
E
E. a mutation that benefits an organism
F. a healthy gene
G. a substance or factor that can cause mutations in DNA
Circle the letter of the best answer.
1. The coat color of the Spirit Bear is due to
a. Change of the seasons
b. Global warming
c. A mutated gene
d. Environmental stresses
2. Most mutations
a. Are helpful to the organism
b. Are harmful to the organism
c. Have no effect on the organism
d. Can be treated in an organism
3. Which of the following is an example of a neutral mutation?
I.
White fur instead of black fur
II.
A mutated gene protects a plant from a disease
III.
Curved red blood cells instead of disc-shaped cells
a. I
B. II
C. III
D. None of the above.
4. Which type of mutation is beneficial to an organism and therefore aids in the organism’s ability to
survive?
a. Neutral
b. positive c. negative d. deletion
5. Errors in the DNA that appear to neither harm nor help an organism are called
a. Neutral
b. positive
c. negative d. substitutions
6. Which of the following can cause mutated genes?
I.
Cigarette smoke
II.
Radiation
III.
Pesticides
a. I and II only
b. I and III only
c. II and III only
d. I, II and III