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Human Genetics
Concepts and Applications
Tenth Edition
RICKI LEWIS
2
Cells
PowerPoint® Lecture Outlines
Prepared by Johnny El-Rady, University of South Florida
1
Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Introducing Cells
Cellular activities and abnormalities underlie
our inherited traits, quirks, and illnesses
Understanding genetic diseases can
suggest ways to treat the condition
Figure 2.1
Lack of
dystrophin
2
Introducing Cells
Our bodies include more than 260 cell types
Somatic (body) cells have two copies of
the genome and are said to be diploid
Sperm and egg cells have one copy of the
genome and are haploid
Stem cells can both replicate themselves
and give rise to differentiated cells
3
Types of Cells
All cells can be divided into two main types
Prokaryotic cells
- Lack a nucleus
Eukaryotic cells
- Possess a nucleus
and other organelles
Figure 2.2
4
Domains of Life
Biologists recognize three broad categories
of organisms
Archaea – Unicellular prokaryotes
Bacteria – Unicellular prokaryotes
Eukarya – Includes both unicellular and
multicellular eukaryotes
5
Chemical Constituents
Cells contain four types of macromolecules
Type
Examples
Functions
Carbohydrates Sugars, starches Energy,
structure
Lipids
Fats, oils
Membranes,
hormones
Proteins
Myosin, collagen Enzymes,
structure
Nucleic Acids DNA, RNA
Genetic
information
6
An Animal Cell
Surrounded by the plasma membrane
Contains:
- Cytoplasm
- Organelles
- Divide labor by partitioning certain
areas or serving specific functions
7
An Animal Cell
Figure 2.3
Figure 2.3
8
The Nucleus
The largest structure in a cell
Surrounded by a double-layered nuclear
envelope
Contains:
- Nuclear pores that allow movement of some
molecules in and out
- Nucleolus, which is the site of ribosome
production
- Chromosomes composed of DNA and
Figure 2.3
proteins
9
The Nucleus
Figure 2.4
Figure 2.3
Figure 2.4
10
Secretion
illustrates
how
organelles
function
together
to
coordinate
the basic
functions
of life
Figure 2.5
11
Mitochondria
Surrounded by two
membranes
Site of ATP (energy)
production
Contain their own
circular DNA
Figure 2.7
Human mitochondrial
DNA is inherited
only from the mother
12
Structures and Functions of
Organelles
Table 2.1
13
Faulty Ion Channels Cause
Inherited Diseases
Sodium channels
- Mutations lead to absence or extreme pain
Potassium channels
- Mutations lead to impaired heart function and
deafness
Chloride channels
- Mutations lead to cystic fibrosis
14
Figure 2.12
15
Cell Division and Death
Normal growth and development require an
intricate interplay between the rates of two
processes
Mitosis – Cell division
- Produces two somatic cells from one
Apoptosis – Cell death
- Precise genetically-programmed sequence
16
Figure 2.13
Figure 2.12
17
The Cell Cycle
The sequence of events associated with cell division
G phase: Gap for
growth
S phase: DNA
synthesis
M phase: Mitosis
(nuclear division)
Cytokinesis: Cell
division
Figure 2.14
18
Stages of the Cell Cycle
Interphase
- Prepares for cell division
- Replicates DNA and subcellular structures
- Composed of G1, S, and G2
- Cells may exit the cell cycle at G1 or enter G0,
a quiescent phase
Mitosis – Division of the nucleus
Cytokinesis – Division of the cytoplasm
19
Replication of Chromosomes
Chromosomes are
replicated during
S phase prior to
mitosis
Figure 2.15
The result is two
sister chromatids
held together at
the centromere
20
Mitosis
Used for growth, repair, and replacement
Consists of a single division that produces
two identical daughter cells
A continuous process divided into 4 phases
- Prophase
- Metaphase
- Anaphase
- Telophase
21
Mitosis in a Human Cell
Figure 2.15
Figure 2.16
22
Prophase
Replicated
chromosomes
condense
Microtubules
organize into a
spindle
Nuclear envelope
and nucleolus
break down
Figure 2.16
23
Metaphase
Chromosomes line
up on the cell’s
equator
Spindle microtubules
are attached to
centromeres of
chromosomes
Figure
Figure2.3
2.16
24
Anaphase
Centromeres divide
Chromatids separate and
become independent
chromosomes
- They move to opposite
ends of the cell
Figure
Figure2.3
2.16
25
Telophase
Chromosomes uncoil
Spindle disassembles
Nuclear envelope
reforms
Figure
Figure2.3
2.16
26
Cytokinesis
Cytoplasmic division occurs after nuclear
division is complete
Organelles and macromolecules are
distributed between the two daughter cells
Microfilament band contracts, separating
the two cells
27
Cell Cycle Control
Checkpoints ensure that mitotic events
occur in the correct sequence
Internal and external factors are involved
Many types of cancer result from faulty
checkpoints
28
Cell Cycle Control
Figure 2.17
Figure 2.16
29
Apoptosis
Begins when a cell receives a “death
signal”
Killer enzymes are activated
-Destroy cellular components
Phagocytes digest the remains
30
Programmed cell death is part of normal development
Figure 2.19
Mitosis and apotosis work
together to form functional body
Cancer can result from too much
mitosis, too little apotosis
31
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Human Genetics: concepts and applications
5th edition
Ricki Lewis
Chapter 3
Development
Replication of chromosomes
•
•
•
•
Replication is the
process of duplicating a
chromosome
Occurs prior to division
Replicated copies are
called sister chromatids
Held together at
centromere
33
Meiosis
a cell division forming gametes
Goal: reduce genetic material by half
Why?
from mom
from dad
child
too
much!
meiosis reduces
genetic content
34
Meiosis: cell division in two
parts
Sister
chromatids
separate
Homologs
separate
Meiosis I
(reduction
division)
Meiosis II
(equational
division)
Diploid
Haploid
Haploid
Result: one copy of each chromosome in a gamete.
35
Meiosis I
(reduction
division)
Meiosis II
(equational
division)
Diploid
Diploid
Haploid
Haploid
Haploid
36
A replicated chromosome
Gene X
sister chromatids
homologs
same genes
same alleles
same genes
maybe different alleles
Homologs separate in
meiosis I and therefore
different alleles separate.
37
Meiosis I : the reduction division
Spindle
fibers
Nucleus
Nuclear
envelope
Prophase I
(early)
(diploid)
Prophase I
(late)
(diploid)
Metaphase I
(diploid)
Anaphase I
(diploid)
Telophase I
(diploid)
38
Prophase I
Early prophase
Late prophase
Homologs pair.
Crossing over occurs.
Chromosomes condense.
Spindle forms.
Nuclear envelope fragments.
39
Metaphase I
Homolog pairs align
along the equator of the cell.
40
Anaphase I
Homologs separate and
move to opposite poles.
Sister chromatids remain
Attached at their centromeres.
41
Telophase I
Nuclear envelopes reassemble.
Spindle disappears.
Cytokinesis divides cell into two.
42
Meiosis II
Gene X
Only one homolog
of each chromosome
is present in the cell.
Sister chromatids carry
identical genetic
information.
Meiosis II produces gametes with
one copy of each chromosome and thus one
copy of each gene.
43
Meiosis II : the equational
division
Prophase II
(haploid)
Metaphase II
(haploid)
Anaphase II
(haploid)
Telophase II
(haploid)
Four
nonidentical
haploid
daughter cells
44
Prophase II
Nuclear envelope fragments.
Spindle forms.
45
Metaphase II
Chromosomes align
along equator of cell.
46
Anaphase II
Sister chromatids separate
and move to opposite poles.
47
Telophase II
Nuclear envelope assembles.
Chromosomes decondense.
Spindle disappears.
Cytokinesis divides cell into two.
48
Results of meiosis
Gametes
Four haploid cells
One copy of each chromosome
One allele of each gene
Different combinations of
alleles for different genes along the
chromosome
49
Mitosis
Meiosis
2
Number of
divisions
1
Number of
daughter cells
2
4
Yes
No
Same as parent
Half of parent
Where
Somatic cells
Germline cells
When
Throughout life
At sexual maturity
Genetically
identical?
Chromosome #
Role Growth and repair Sexual reproduction
50
Recombination (crossing over)
•
Occurs in prophase of
meiosis I
A
A
B
B
C
•
Generates diversity
b
C
D D
E
F
e
E
F
a
a
f
c
b
c
d
d
e
f
•Creates chromosomes with new
combinations of alleles for genes A to F.
51
Recombination (crossing over)
•
Occurs in prophase of
meiosis I
A
a
B
C
•
Generates diversity
Letters denote genes
Case denotes alleles
C
c
D D
E
F
d
E
F
e
f
b
c
d
e
f
•Creates chromosomes with new
combinations of alleles for genes A to F.
52
Recombination (crossing over)
•
Occurs in prophase of
meiosis I
a
A
B
b
C
•
Generates diversity
Letters denote genes
Case denotes alleles
D
E
F
A
a
B
c
b
c
d
d
C
D
E
F
e
f
e
f
•Creates chromosomes with new
combinations of alleles for genes A to F.
53
Independent assortment
The homolog of one chromosome can be inherited
with either homolog of a second chromosome.
54
Clones
•
•
•
A clone is a collection
organisms derived from the
same original cell.
Genetically identical
Phenotype may differ
because of different life
history.
Calves cloned share genes.
variation in coat patterns
reflect migration of cells
during development
55
Figure 8.14
MEIOSIS I
MITOSIS
Parent cell
(before chromosome duplication)
Prophase
Duplicated
chromosome
(two sister
chromatids)
Chromosome
duplication
Site of
crossing
over
Prophase I
Tetrad formed
by synapsis of
homologous
chromosomes
Chromosome
duplication
2n  4
Metaphase I
Metaphase
Chromosomes
align at the
metaphase plate
Tetrads (homologous
pairs) align at the
metaphase plate
Anaphase I
Telophase I
Anaphase
Telophase
Homologous
chromosomes
separate during
anaphase I;
sister
chromatids
remain together
Sister chromatids
separate during
anaphase
Daughter
cells of
meiosis I
Haploid
n2
MEIOSIS II
2n
2n
Daughter cells of mitosis
No further
chromosomal
duplication;
sister
chromatids
separate during
anaphase II
n
n
n
n
Daughter cells of meiosis II
56