Download chromosomes review answers

CHROMOSOMES REVIEW
ANSWERS
Answer to Question #1
Answer to Question #2a
• WHERE IS DNA LOCATED INSIDE THE CELL? Eukaryotic cells?
Where in prokaryotic cells? When do chromosomes
become visible?
• FOR EUKARYOTIC CELLS IN THE
NUCLEUS
• FOR PROKARYOTIC CELLS IN THE
CYTOPLASM
• DURING MITOSIS OF THE CELL CYCLE
AFTER G2
Answer to Question #2b
Draw and label anucleotide
Monomer..
Answer to Question #2c
WHAT IS THE STRUCTURE THAT ALLOWS DNA TO MAINTAIN A
RIDGID SHAPE?
• Chromosomes are made up of
2 chromatids joined together
at the centromere. Chromatids
are made of chromatin wrapped
around a protein called histone
that allows DNA to maintain rigid
shape.
Answer to Question #2d WHAT IS THE
NITROGEN BASE PAIRING RULE?
• The complementary base pairing rule
says that purines bond to pyrimidines. G
always bonds to C with 3 hydrogen
bonds. A bonds to T with 2 hydrogen
bonds?
Answer to Question #2e DRAW A PURINE BONDED TO
A PYRIMIDINE. NAME ALL THE BASES FOR EACH TYPE.
HOW MANY HYDROGEN BONDS BETWEEN EACH
PAIR?.
Purines are
Adenine and
Guanine
Pyrimidines
are Thymine
and Cytosine
Answer to Question #3b COMPLETELY DESCRIBE THE
STRUCTURE OF A CHROMOSOME.
• Chromosomes are made up of
2 chromatids joined together
at the centromere. Chromatids
are made of chromatin wrapped
around a protein called histone
Answer to Question #3c LABEL ALL PARTS OF
THE CELL AND CHROMOSOME. WHEN ARE
CHROMOSOMES VISIBLE INSIDE CELLS?
• CHROMOSOMES
ARE ONLY VISIBLE
DURING MITOSIS OF
THE CELL CYCLE
Answer to Question #3d DEFINE GENE AND LIST
A BRIEF FUNCTION.
• How many base pairs in a gene?
– Average is 27 thousand.
• Largest 2.4 million base pairs.
• How many in a chromosome?
• Between 50 and 250 million.
A gene is the basic physical and functional unit of
heredity. Genes, which are made up of DNA, act as
instructions to make molecules called proteins.
Answer to Question 4a. LIST 3 EXAMPLES OF
CARCINOGENS? HOW DO THEY DAMAGE CELLS?
• Carcinogens,
radiation inhaled
asbestos, certain
dioxins, and
tobacco smoke.
A carcinogen is a substance that causes a
normal cell to change into a cancerous cell,
resulting in uncontrolled cell growth.
Answer to Question 4b. WHICH CELLS HAVE A
HAPLOID NUMBER? DIPLOID?
HAPLOID -Cells with
½ the number of
chromosomes as
diploid for sexual
Reproduction
DIPLOID – Cells with
2x the haploid
number or
body/somatic cells
Answer to Question 4c. DESCRIBE THE
PROCESS OF FERTILIZATION.
• Fertilization is the union
of a human egg and
sperm, usually occurring
in uterine tube. The result
of this union is the
production of a zygote, or
fertilized egg
Answer to Question 5a. DESCRIBE THE
KARYOTYPE OF A HUMAN.
KARYOTYPE is a picture of an
A __________
organism’s chromosomes
Chromosomes that determine
Sex chromosomes
the sex of an organism = _________________
autosomes
All other chromosomes = _________________
Humans have two sex chromosomes
44 autosomes
and _____
X Y = boy
XX = girl
Answer to Question 5c. DOES MORE CHROMOSOMES = MORE
COMPLEX ORGANISM - GIVE A PROPORTION SENTENCE TO
ANSWER NOT YES OR NO? WHAT IS A HOMOLOGUE?
• Bacteria have one, fruit flies
have four pairs, and a plant
called the Adder's Tongue
Fern has over 1,000 pairs!
The number of
chromosomes is not what
makes an organism
genetically unique.
Species are unique because
of the content of the DNA,
not the number of
chromosomes.
Answer to Question 5d. WHAT IS A
HOMOLOGUE?
• All sexually reproducing organisms have
chromosomes that occur in pairs. These pairs
separate during meiosis and are called
homologous pairs. Each individual
chromosome is a homologue.
Homologous chromosomes
fail to separate
________________
during MEIOSIS
NONDISJUNCTION
= __________________.
One cell gets 2 copies of
the chromosome the
other cell gets none.
Human Abnormalities caused by
Non-Disjunction
Down syndrome
__________________
Klinefelter syndrome
__________________
Turner syndrome
__________________
Patau syndrome
__________________
Answer to Question 6c. WHEN SPECIFICALLY DOES NON-DISJUNCTION
OCCUR DURING MEIOSIS? WHAT IS SYNAPSIS? WHEN DOES IT OCCUR?
WHAT IS CROSSING OVER? WHEN DOES IT OCCUR? WHAT EVENT LEADS TO
HUGE AMOUNT OF VARIATION AMONG OFFSPRING?
• Nondisjunction in
meiosis I occurs during
anaphase I when one
pair of homologous
chromosomes fails to
separate.
Answer to Question 6d. WHAT IS SYNAPSIS? WHEN DOES IT
OCCUR? WHAT IS CROSSING OVER? WHEN DOES IT OCCUR?
WHAT EVENT LEADS TO HUGE AMOUNT OF VARIATION AMONG
OFFSPRING?
• Synapsis is the pairing of
homologous chromosomes during
prophase 1 of meiosis
• Crossing over is the exchange of a
portion of a chromosome with its
homologous partner which also
occurs during prophase 1 of meiosis
• Independent assortment leads to
large variation in populations and
ultimately to the evolution of species
better adapted to live in a particular
environment
Answer to Question 7a. DRAW AND LABEL THE PARTS OF THE
CELL CYCLE. WHICH CELLS REMAIN IN G0 (PERMANENT
INTERPHASE
**During the G0
phase, the cell
cycle machinery
is dismantled.
Cells then
remain in the G0
phase until
there is a reason
for them to
divide.
***muscle and
nerve cells***
Answer to Question 7b. SKETCH AND LABEL 4 STAGES
OF MITOSIS. LABEL CHROMOSOMES, SPINDLE FIBERS,
CENTRIOLES, EQUATOR, CENTROMERE. WHICH CELLS
DIVIDE BY MITOSIS?
• Somatic or body cells divide by mitosis. Cells
that remain in G0 no longer divide by mitosis.
Nerve cells are an example
10.
Equator
Answer to Question 8a. WHAT IS MEIOSIS? SKETCH
AND LABEL THE STEPS IN MEIOSIS.
• Meiosis is the process that makes 4 cells
genetically different from parent cell & from
each other. Makes 1n cells used for sexual
reproduction.
Answer to Question 8b. LIST 4 WAYS MEIOSIS IS DIFFERENT THAN MITOSIS.
WHAT IS INDEPENDENT ASSORTMENT? LIST 2 SOMATIC CELLS . (I KNOW
THESE LAST TWO ARE REPEATS FROM AN EARLIER QUESTION
• Mitosis occurs in somatic cells (skin, blood, etc.)
Meiosis occurs only in sex cells (sperm, egg, pollen, ovule)
• Mitosis results in two diploid cells
Meiosis results in four haploid cells.
• Mitosis: homologous chromosomes do not pair.
Meiosis: homologous chromosomes pair up.
• Mitosis: crossing over does not occur.
Meiosis: crossing over occurs at points called chiasmata.
• Mutations that occur during mitosis are not passed on to offspring,
mutations that occur during meiosis may be passed to succeeding
generations.
Answer to Question 9a. IDENTIFY THE DISORDERS IN
THE KARYOTYPES BELOW. TELL THE SEX OF EACH
INDIVIDUAL. LIST 3 MAJOR CHARACTERISTICS OF
EACH SYNDROME.
Answer to Question 9b. IDENTIFY THE DISORDERS IN
THE KARYOTYPES BELOW. TELL THE SEX OF EACH
INDIVIDUAL. LIST 3 MAJOR CHARACTERISTICS OF
EACH SYNDROME.
• Klinefelters syndrome
• Male
– sparse body hair
– enlarged breasts
– wide hips
– testicles remain small
– penis does not reach
adult size
Answer to Question 9c. IDENTIFY THE DISORDERS IN
THE KARYOTYPES BELOW. TELL THE SEX OF EACH
INDIVIDUAL. LIST 3 MAJOR CHARACTERISTICS OF
EACH SYNDROME.
•
•
•
•
Jacob’s syndrome
Male
learning disabilities
delayed development of
speech and language
skills.
• Delayed development of
motor skills (such as
sitting and walking
• hand tremors or other
involuntary movements
(motor tics
• abehavioral and
emotional difficulties are
also possible
Answer to Question 9d. IDENTIFY THE DISORDERS IN
THE KARYOTYPES BELOW. TELL THE SEX OF EACH
INDIVIDUAL. LIST 3 MAJOR CHARACTERISTICS OF
EACH SYNDROME.
• Patau syndrome
• Female
– Cleft lip or palate
– Clenched hands (with outer
fingers on top of the inner
fingers)
– Close-set eyes -- eyes may
actually fuse together into one
– Decreased muscle tone
– Extra fingers or toes
(polydactyly)
– Low-set ears