DNA, RNA, & Meiosis
Review
CPBiology
Ms. Morrison
1. Diagram and label a model of
DNA. Include the parts that make
up a single nucleotide.
• 3 parts to
nucleotide:
– 5 carbon sugar
(deoxyribose)
– Phosphate group
– Nitrogenous base
(A, T, C, and G)
2. Describe in detail how DNA
replicates itself.
1.
2.
3.
4.
DNA molecules unzips into two strands
Complementary nucleotides pair with the two
strands
DNA polymerase binds the nucleotides together
and “proofreads” the DNA
Two new DNA strands – each with one original
strand and one new strand
(Note: prokaryotes starting replicating at one single point,
while eukaryotes start replicating at many points)
3. Differentiate between DNA and
RNA.
Difference
DNA
RNA
Bases
thymine (T)
uracil (U)
Sugars
Deoxyribose
Ribose
Appearance
double strand
(double helix)
single strand
4. Compare DNA and RNA by
checking the appropriate box:
DNA mRNA tRNA rRNA
Deoxyribonucleic acid
√
Ribonucleic acid
√
√
√
Ribose present
√
√
√
√
√
√
Deoxyribose present
√
Phosphate present
√
4. Compare DNA and RNA by
checking the appropriate box:
DNA mRNA tRNA
Adenine present
√
Thymine present
√
Uracil present
rRNA
√
√
√
√
√
√
Guanine present
√
√
√
√
Cytosine present
√
√
√
√
4. Compare DNA and RNA by
checking the appropriate box:
DNA mRNA tRNA rRNA
Made of nucleotides
√
Double stranded
√
Single stranded
Remains in the nucleus
√
Contains a chemical
message or code
√
√
√
√
√
√
√
√
5. List the main function for each
of the following types of RNA:
1. mRNA – contains instructions for
assembling amino acids into proteins
from DNA
2. rRNA – make up ribosomes along
with proteins
3. tRNA – transfers amino acids to
ribosome as specified by DNA
6. Summarize the process (steps)
of transcription.
1. RNA polymerase binds to DNA
2. RNA polymerase separates DNA strands
3. One strand of the DNA is used as a
template to make complementary mRNA
strand
4. mRNA strand edited before leaving
nucleus with message to code for
proteins
7. Summarize the process (steps) of
translation.
1.
2.
3.
4.
5.
6.
The mRNA strand attaches to ribosome.
Start codon on mRNA (AUG) is read and tRNA
with anticodon attaches the amino acid
(methionine).
The next tRNA with the correct amino acid
binds to the 2nd mRNA codon.
The ribosome forms a peptide bond between the
two amino acids.
The mRNA strand moves through the ribosome
binding amino acids to the growing polypeptide
chain.
When the stop codon is reached on the mRNA
strand, the mRNA strand and the completed
protein is released from the ribosome.
7. Summarize the process (steps)
of translation.
7. Summarize the process (steps)
of translation.
8. Determine the mRNA, tRNA,
and amino acid sequence for the
following DNA strand.
DNA
TAC
AAA
CCA
TTG
CGA
AAT
AGA
TGA
ATT
mRNA
AUG
UUU
GGU
AAC
GCU
UUA
UCU
ACU
UAA
tRNA
UAC
AAA
CCA
UUG
CGA
AAU
AGA
UGA
AUU
Amino
acid
Methio
nine
Phenyla
lanine
Glycin
e
Aspar
agine
Alanine
Leucine
Serine
Threoni
ne
STOP
9. Contrast gene and chromosome
mutations.
• Gene mutations affect the DNA sequence which
will change the protein that the gene codes for.
There are two types:
– Point mutations – single base substituted for another so
only one amino acid affected
– Frameshift mutation – single base added or deleted so
all amino acids changed after mutation
• Chromosome mutations affect the entire
chromsomes and all the genes located on it,
examples:
– Extra copy of a chromosome
– Only one copy of a chromosome instead of two
(homologous)
– Missing part of chromosome or have extra genes
attached
10. Explain why some changes in
DNA structure are inherited and
some are not.
Only changes that occur in gametes
(egg or sperm cells) can be passed on
to offspring (inherited). If the
changes occur in body cells, then only
that organism is affected.
11. Identify which type of mutation has
occurred in the original DNA sequence.
Underline all the mutated codons.
DNA: TAC TTA CCG TCA ATT
a.
TAC TCT ACC GTC AAT T
frameshift mutation (insertion)
b.
TAC TTA CGT CAA TT
frameshift mutation (deletion)
c.
TAC TTA CCG ACA ATT
point mutation
12. Diagram the phases of meiosis in an
animal cell with 4 chromosomes. Explain
what happens in each phase.
• Meiosis I (with one cell)
– Prophase I – homologous chromosomes (replicated during
Interphase I) pair up in tetrads while spindle forms and
nuclear membrane disappears, crossing over can occur
– Metaphase I – homologous chromosomes line up in middle
of cell and spindle fibers attach to them
– Anaphase I – homologous chromosomes are pulled to
opposite sides of cell by spindle fibers
– Telophase I – nuclear membrane reforms around the
separated homologous chromosomes, spindle breaks
down, cell divides into two haploid cells
12. Diagram the phases of meiosis in an
animal cell with 4 chromosomes. Explain
what happens in each phase.
12. Diagram the phases of meiosis in an
animal cell with 4 chromosomes. Explain
what happens in each phase.
• Meiosis II (with two cells)
– Prophase II – nuclear membranes disappear and spindle
forms (no DNA replication occurs during Interphase II)
– Metaphase II – sister chromatids (chromosomes) line up
along center of cell and are attached to spindle fibers
– Anaphase II – sister chromatids are separated and
pulled towards opposite sides of the cell
– Telophase II – nuclear membranes reform around the
chromatids and the spindle breaks down, the two cells
divide into four haploid cells
12. Diagram the phases of meiosis in an
animal cell with 4 chromosomes. Explain
what happens in each phase.
13. How do the results of meiosis
differ in female organisms from
male organisms?
• Males – one gamete forms four sperm
cells in even meiotic divisions
• Females – one gamete forms one egg
cell with most of the cytoplasm and
three polar bodies which are NOT
used in reproduction, this occurs
because of uneven meiotic divisions
14. Differentiate between haploid and
diploid cells. Using a human cell, explain
how the number in each are different.
• Diploid means having two homologous
chromosomes – similar chromosomes where one is
from the male parent and the other is from the
female parent
• Haploid means having a single chromosome (only
from one parent)
• Humans have 23 pairs of chromsomes for a total
of 46 chromosomes – this is diploid
• Human gametes (eggs, sperm) have 23
chromosomes (therefore when egg and sperm
combine – a cell is produced with 46 chromosomes
or 23 pairs of chromosomes)
15. Compare mitosis to meiosis.
Mitosis
Meiosis
Kind of cell used
body cell
germ cell
Kind of cell made
(diploid or haploid)
diploid
haploid
# of cells made
two
four
# of chromosomes
in daughter cells
compared to
original cell
same #
(diploid)
half the #
(haploid)
Number of cycles
one division
two divisions
15. Compare mitosis to meiosis.
Mitosis
Meiosis
Differences
in Interphase
DNA is replicated
so duplicate copy
for division
I – DNA replicated
so duplicate copies
of chromosomes
II – NO replication
Differences
in Prophase
Nuclear membrane
disappears, spindle
forms,
chromosomes
become visible
I – same as mitosis,
but tetrads form
between
homologous
chromosomes pairs
and crossing over
can occur
II – same as mitosis
15. Compare mitosis to meiosis:
Mitosis
Meiosis
Differences
in Metaphase
Sister chromatids
line along center of
cell and are
attached to spindle
fibers
I – similar to
mitosis but it is the
homologous
chromosome pairs
that line up
II – same as mitosis
Differences
in Anaphase
Sister chromatids
are separated and
pulled to opposite
ends of cell
I – Homologous
pairs are separated
and pulled to
opposite ends of
cell
II – same as mitosis
15. Compare mitosis to meiosis:
Differences
in Telophase
Mitosis
Meiosis
Nuclear membranes
reform around
separated
chromatids, spindle
breaks down, and
cell divides – two
diploid daughter
cells formed
I – same as mitosis,
but is a duplicated
chromosome and
when the cell
divides each
daughter cell is
haploid
II – same as mitosis
but two cells divide
to form four
haploid cells