part of exercise 4 of human anatomy & physiology laboratory manual, 8th edition, by elaine...
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Part of Exercise 4 of Human Anatomy & Physiology Laboratory Manual, 8th Edition, by Elaine Marieb
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Dr.Susan Maskel BIO 105 Western Connecticut State University A&P I
BIO 211 Naugatuck Valley Community College A&P I
Some graphics and all definitions courtesy of Benjamin Cummings
www.lawrencegaltman.com
Background
Information
CHROMOSOMES
DNA (deoxyribonucleic
acid) stores genetic information
Protein
controls processes
DNA2 strands double helixeach strand contains:
sugars (deoxyribose)
phosphates (PO4)nitrogenous bases
adeninethymineguaninecytosine
Structure of Components of DNA
-O - P = O
O-
O
phosphate
DNA
S
S
S
S
P
P
P
B
B
B
B
B
B
B
B
S
S
S
S
P
P
P
PPS B B S
Key:
S = sugar
P = phosphate
B = base
sugar-phosphate backbone
nitrogenous bases form “rungs of ladder”
Bases in DNA
•Adenine (A)•Thymine (T)•Cytosine (C)•Guanine (G)
•Specificity of base pairing A - T C - G
DNA
Types of Chromosomes
duplicated (2 ds DNAs +
protein)
unduplicated (1 double stranded (ds) DNA + protein)
Duplicated Chromosomes
DNA
sister chromatids
centromere
Humans have 46 chromosomes in their somatic (i.e., not sperm or
egg) cells.
Diploid number = 2 N = 46
Humans have 23 chromosomes in their sex cells (sperm & egg).
Haploid number = 1 N = 23
THE CELL CYCLE
not dividing
dividing
At any given time, a cell is either:
When Cells are Not Dividing:• Interphase
– G1•Normal cell metabolism•Synthesis of proteins not used for mitosis•Chromosomes unduplicated•Centrioles replicate
– S•Normal cell metabolism•DNA synthesis (DNA replication):
unduplicated chromosomes duplicated chromosomes
– G2•Normal cell metabolism•Synthesis of proteins used for mitosis•Chromosomes duplicated
• DNA unzips• New nucleotides
(sugar-phosphate-base combinations) add according to specificity of base pairing
DNA Replication
old strand
new strand
forming sister chromatid of duplicated
chromosome
NOTE:
The 2 forming sister
chromatids have an
identical base
sequence to each
other.
Semiconservative Replication: each
sister chromatid has 1 new & 1 old
strand
ds DNA of unduplicate
d chromosom
e
sister chromatids
of duplicated
chromosome
When Cells Are Dividing:• Nuclear Division
–Mitosis•occurs in somatic cells•maintains the # of chromosomes
–Meiosis•occurs in sex cells•halves the # of chromosomes
• Cytokinesis–division of cytoplasm–occurs during mitosis & meiosis
G1 unduplicated chromosomes
S chromosomes
duplicate
G2 duplicated
chromosomesM
start with duplicated
chromosomes; end with
unduplicated chromosomes
Before mitosis begins,
the cell is in INTERPHASE.
INTERPHASE
•cell is not dividing•includes G1, S & G2•nuclear membrane
visible•nucleoli visible•chromatin in nucleus•NOT PART OF MITOSIS
Interphase
-nuclear membrane intactnucleolus visiblechromatin not visible
NOTE:
Interphase
Nuclear membrane present Chromatin not
visible
Interphase
Nuclear division in
somatic cells takes place via
MITOSIS.
prophase
metaphase
anaphase
telophase
PROPHASE (1 - several hours)
• nuclear membrane disappears• nucleoli disappear• chromatin chromosomes• centrioles move to opposite
poles of cell• spindle & asters form
Centrioles
made of microtubule
s
at end of G1,
centrioles replicated (to form 2
pairs)
Spindle & Asters
aster
probably anchors apparatus to cell
membrane
spindle
helps organize
chromosomes during mitosis
Prophase
In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.
nuclear membrane disappears nucleolus disappearschromatin chromosomesspindle & asters form
NOTE:
Prophase
Nuclear membrane still present but is
disappearing
chromosomes
Prophase
METAPHASE (5 - 15 minutes)
•chromosomes line up on center of spindle
•chromosomes are attached to spindle fibers in area of centromere
Metaphase
In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.
chromosomes lined up in single file in center of
spindle
NOTE:
Metaphase
Chromosomes lined up on center of
spindle
aster
aster
Metaphase
ANAPHASE (2 - 10 minutes)
•spindle fibers pulled toward opposite poles of cell
•centromeres splits•sister chromatids pulled
toward opposite poles of cell as microtubules of spindle shorten
Anaphase
In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.
NOTE:
sister chromatids being pulled toward opposite
poles of cell
Anaphase
chromatids separated & being pulled toward opposite poles of cell
aster
aster
Anaphase
TELOPHASE (10 - 30 minutes)
• cleavage furrow formed• cell invaginates at cleavage
furrow until 2 daughter cells formed (= cytokinesis)
• opposite of prophase– nuclear membrane reappears– nucleoli reappear– chromosomes uncoil to
chromatin– spindle & asters disappear
Telophase
In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.
NOTE:
cleavage furrow forms;2 daughter cells will form; the opposite of prophase will occur
Telophase
unduplicated chromosomes unwinding
unduplicated chromosomes unwinding
cleavage furrow
Telophase
spindle
INTERPHASE PROPHASE METAPHASE
ANAPHASE TELOPHASE TELOPHASE
Part of Exercise 4 of Human Anatomy & Physiology Laboratory Manual, 8th Edition, by Elaine Marieb
Dr.Susan Maskel BIO 105 Western Connecticut State University A&P I
BIO 211 Naugatuck Valley Community College A&P I
Some graphics and all definitions courtesy of Benjamin Cummings
www.lawrencegaltman.com
Name the phase of mitosis
indicated.
Answer: metaphase
Name the phase of mitosis
indicated.
AnswerAnaphas
e
Name the phase of mitosis seen.
ANSWER: prophase
Name the phases of mitosis indicated.
1
2
3
4
ANSWERS
1
2
3
4
1 = metaphase
2 = telophase
3 = anaphase
4 = prophase
Name the phases of mitosis indicated.
12
3
ANSWERS
12
3
1 = anaphase
2 = metaphase
3 = anaphase
Now it’s YOUR turn to identify stages of mitosis
with a microscope!