Bio 1 General Biology – Exam 3 Outline
Cell Division & Reproduction (Chapter 9, 10, & 12)
During this lecture, you will learn…
1) What it is that one generation passes on so that the next generation can be formed.
2) What controls the development of a living thing as it goes from being a microscopic cell to a larger organism.
3) How it is that the adult body is able to build muscle or repair a wound.
I. The Role of DNA in Cell Division
A. What controls cell reproduction/development?
B. DNA contains an organism’s genome (the complete set of that organism’s genetic information strung together in
functional units called genes that lay long the double helix)
1. Human genome is 3 billion base pairs long and includes 20,000 – 25,000 genes. We are born with a huge
volume of info that has been amassed and edited over 3.8 billion years of evolution.
2. There is not just one copy of this genome in an organism. Most cells in an organism contain a complete copy
of that organism’s genome. A given cell expresses or puts to use only parts of this genome. Different genes
are active in different cells. This is what distinguishes a liver cell from a muscle cell.
3. Cells duplicate yet they still have a complete set of a genome, so the genome must duplicate too.
C. What is passed on to the next generation?
II. DNA & Chromosomes
A. DNA is not just one long straight, double helix. It is divided up and packaged into units called chromosomes
“colored bodies” (Fig. 9.6).
1. Chromosomes
a. Each chromosome contains a
single, long DNA molecule
bearing thousands of genes.
b. Number of chromosomes in a cell, like
the number of genes, depends on the
species. (Ex. humans cells = 46, onion
cells = 15, dog = 78)
c. Most of time, chromosomes exist as
diffuse mass of very long fibers (the total DNA in a single human cell’s 46 chromosomes would stretch
to about 6 feet long!)
d. As cell prepares to divide, its fibers coil up, forming
compact chromosomes and then are clearly visible
under the microscope. (Fig. 9.8)
2. Sister chromatids (Fig. 9.6)
B. Matched pairs (homologous) of chromosomes (Fig. 9.7)
1. A typical body cell (somatic cell) in humans has 46
chromosomes.
2. Chromosomes come in pairs that are close but not
exact matches.
3. The 46 chromosomes we have come to us as 23
chromosomes pairs, 23 from each parent; each
chromosome from mother matching with one from
father.
Ex. one from father coding for red hair while one
from mother codes for blond hair
4. Homologous chromosomes carry the same sequence of
genes controlling the same inherited characteristics. If a
gene influencing eye color is located in a particular
place on one chromosome then the homologous
chromosome has a similar gene for eye color there.
However the two genes may be slightly different
versions (Ex. blue from dad and brown from mom)
You are the product of the specific genes that are being expressed!
C. Exception to the matched pairs rule (Fig. 9.7)
How does a baby grow, a plant develop, or a wound heal?
III. Cell Division
A. Steps of cell division (Cell Cycle): (Fig. 9.9)
1. Interphase (G1, S, & G2 phases)
2. Mitotic Phase (M phase)
a. Mitosis
b. Cytokinesis
3. How long does this cycle take?
a. As many as 25 million cell divisions
are happening in your body every
second!
b. Most human brain cells are formed in first 3 months of embryonic existence and live for decades, with
very few of them dividing again. Stem cells in human bone marrow never stop dividing as they produce
blood cells
B. Mitosis – cell division that produces body cells for organism growth and maintenance. Cell division of somatic
cells (all cells in organism except for those that become eggs or sperm)
Steps of Mitosis: (Fig. 9.10) Prophase, Metaphase, Anaphase, Telophase (PMAT)
Mitosis produces somatic (body) cells for organism growth and maintenance!
View course website animations on Mitosis
IV. When Mitosis Goes Wrong
Cancer – disease of the cell cycle
Cancer cells have malfunctioning cell cycle control systems so they divide excessively
Go to this website: http://www.cancer.gov/ , click on “What Is Cancer? ” under the heading “Cancer
Topics” and read about the following types of cancers and tumors:
A. Types of cancers are named according to where they start, so state the tissues or body system that they start in:
1. Carcinoma
2. Sarcoma
3. Leukemia
4. Lymphoma/myeloma
B. Types of Tumors: Define each tumor type
1. Benign tumor
2. Malignant (metastatic) tumor
C. Cancer Treatments
1. Radiation therapy – tumors are exposed to high energy radiation which disrupts cell division
2. Chemotherapy – uses drugs to disrupt cell division
Ex. Vinblastine - obtained from the periwinkle plant native to tropical rainforests in Madagascar
Taxol - found in bark of the Pacific yew tree found mainly in northwestern U.S.
Since cancer cells are more likely to be dividing at any given time than normal cells, radiation and
chemotherapy can often destroy cancer cells without seriously injuring normal cells. However, damage to
normal cells sometimes occurs and causes nausea, hair loss, and possible sterility
3. Hormonal therapy – prevents cells from receiving hormonal signals needed for cell growth and division
Ex. Tamoxifen
4. Biological therapy (Immunotherapy) – uses the body's immune system to fight cancer
D. Prevention of Cancer
Go to this website: http://www.cancer.gov/ , click on “Prevention, Genetics, Causes” under the heading
“Cancer Topics”, click on “Cancer Prevention”, and then click on “Cancer Trends Progress Report:
Prevention”. List strategies that can reduce your risk of cancer.
V. Another Type of Cell Division
A. Meiosis – cell division that produces the reproductive
cells that give rise to succeeding generations. Cell
division of germ-line cells which are called oogonia
(cells that produce eggs) and spermatogonia (cells that
produce sperm). Eggs and sperm are also called
gametes.
1. Gametes fuse to make a zygote (embryo) which
grows into a whole organism.
2. Each human body (somatic) cell has 23 pairs of
chromosomes or 46 chromosomes. If an egg and
sperm each brought 46 chromosomes to their union,
the result would be a zygote with 92 chromosomes,
the next would have 184, the next would be 368 and
so on.
B. How do chromosomes avoid the problem of doubling
with each generation?
1. Haploid (n)
2. Diploid (2n)
Meiosis now means:
C. Phases of Meiosis:
1. First Meiotic Division (Meiosis I)
2. Second Meiotic Division (Meiosis II)
Steps in Meiosis I (Fig. 10.2):
Crossing Over (Fig. 10.3)
Independent Assortment (Fig. 10.4)
Now each cell divides again because cells still have duplicated chromosomes.
Steps in Meiosis II (Fig. 10.2):
Meiosis produces haploid germ line cells (egg and sperm = gametes) for producing another individual!
View course website animations on Meiosis
D. Gamete Formation in Humans
Read p. 182-185 “Gamete Formation in Humans” and answer the following:
1. What are the starting female cells and starting male cells in gamete formation called? Are they haploid or
diploid?
2. Why are spermatogonia considered sperm-producing factories and how along can males keep producing
sperm?
3. When are oogonia produced in large numbers in females? Do adult females have reproductive stem cells
like males?
4. Explain when meiosis I and meiosis II occur in females.
E. Why Meiosis is Important
1. Is the chromosome duplication problem solved?
2. Meiosis provides two sources of genetic variation (ways for genetic diversity to exist among organisms)
(Fig. 10.3 & 10.4)
a. How many configurations of chromosomes can occur?
- How many sides can they line up on?
- How many chromosomes in a gamete?
- ____________________ possible line up configurations can occur! If you had 8.4 million eggs or
sperm, each one would be slightly different from each other!
- How likely is it that the egg that produced you will have the same line up configuration as the egg
that produced your sibling?
- How many possible chromosome combinations are there when an egg and sperm unite during
fertilization?
- This means that if one couple was to have 64 trillion babies, each baby would be genetically
different. Remember genes on these chromosomes code for eye color, hair color, height, etc. Now
that’s a lot of genetic and physical variation!
- The shuffling of genetic material that occurs during meiosis and random fertilization are the reasons
why children look different from their parents and from each other!
View course website animations on Genetic Variation
b. What else is this diversity responsible for?
Read p.181-182 “Diversity in the Living World” and answer the following:
1. What is this diversity responsible for?
2. How did the natural world come to be such a remarkably diverse place? Also, describe a brief
example of this.
3. The dark frog was selected for survival by undergoing what is called _______________________.
3. Important in sex determination (Fig. 10.7)
a. Individuals with one X and one Y are ___________ and those with two Xs
are _____________.
b. Human males and females both have 44 autosomes (chromosomes other
than sex chromosomes). Because of meiosis, each gamete (egg or sperm)
contains one sex chromosome and a haploid set of autosomes (22 in
humans).
c. All eggs contain a single X chromosome; half of sperm cells will contain
X and other half will contain Y.
d. Which parent determines the sex of a child?
E. When Meiosis Goes Wrong
1. Nondisjunction (Fig. 12.7)
a. Aneuploidy
Meiosis
2. Conditions caused by nondisjunction:
a. Individual may not have the standard number of autosomes. (Fig. 12.8)
Example?
b. Individual may not have the standard number of sex chromosomes.
Example? Sex Chromosome Abnormalities:
- Turner syndrome = XO (only 45 chromosomes instead of 46); female hormone deficiencies at puberty; can be t
- Trisomy = XXX; most have no detectable defects; still fertile
3. Mistakes in cell division can lead to new species.
Polyploidy – when one or more entire sets of chromosomes have been added
a. At least half of all flowering plants are polyploid
b. In plants, if meiosis fails to occur in reproductive organs and gametes are produced by mitosis the
gametes will be diploid (2n) and will produce a tetraploid (4n) offspring and may develop into a mature
tetrploid plant that can reproduce by self-fertilization. The tetraploid plants will make up a new species
in just one generation.
F. Read p. 222-223 “PGD: Screening for a Healthy Child” and answer the following:
1. State what “PGD” stands for and briefly describe how this process is done.
2.
State the two main reasons why couples use PGD.
3.
State the ethical issues surrounding PGD.
VI. Reproduction of Organisms
A. Sexual Reproduction
Examples?
B. Asexual Reproduction
Examples?
Advantages and disadvantages of each type?
VII. Mitosis vs. Meiosis
Mitosis
What type of cells is produced from
this type of cell division?
Is the cell haploid or diploid before
cell division?
Is the cell that is produced after cell
division haploid or diploid?
Will this type of cell division produce
exact copies of or genetically
different cells?
Why is this type of cell division
needed by organisms?
Meiosis
Biotechnology (Chapter 15)
Biotechnology
I.
Transgenic Biotechnology (Fig. 15.5)
A. Transgenic organism – an organism whose genome has
incorporated one or more genes from another species
B. Recombinant DNA – segments of DNA that have been
combined into a sequence that does not exist in nature
C. Examples of this technology
1. Transgenic Microbes & Cells
2. Transgenic Livestock
3. Transgenic crops (genetically modified crops)
Read p. 278: “Controversies in Biotechnology: Genetically Modified Foods” and the online articles “The
Risks on the Table” and “Biotech Foods Are Still Hard to Swallow” and answer the following:
1. Describe three specific concerns surrounding genetically modified foods (be specific).
Different cells with specific functions contain a complete set of DNA which means that cells have the potential to act
like every other cell if its pattern of gene expression is altered.
II. Cloning & Stem Cells
A. Reproductive Cloning (Fig. 15.8)
1. What is the goal of this type of cloning?
2. Advantages & disadvantages of reproductive cloning?
B. Therapeutic Cloning
1. What is the goal of this type of cloning?
2. Embryonic stem cells – cells in an early animal embryo that have not specialized yet. They will specialize
during development to give rise to all cell types in the body
a. When grown in lab can divide indefinitely and can be induced to specialize into a particular cell type.
3. Adult stem cells – partly specialized cells found in an adult’s body that constantly divide and produce new
cells (i.e. skin cells, cells in bone marrow that produce blood cells, etc.)
4. Advantages & disadvantages of stem cell research?
Watch the online video “Stem Cells Breakthrough” and answer the following questions:
http://www.pbs.org/wgbh/nova/sciencenow/0305/03.html
1. Why are embryonic stem cells also called pluripotent cells?
2. What type of adult cell have scientists been able to turn into embryonic stem cells?
3. Is it true that virtually all cells in the body have the same DNA?
4. What happens to our genes during embryonic development which leads to the production of different cell types?
5. What needs to be done to the genes in a skin cell to turn it back into an embryonic stem cell?
6. What are these induced stem cells called?
Watch the online video “Anthony Atala on growing new organs” and answer the following questions:
http://www.ted.com/talks/lang/eng/anthony_atala_growing_organs_engineering_tissue.html
1. What organ was the first to be transplanted in humans?
2. How often does a patient die from diseases that could be treated with tissue replacement?
3. How often do your bones regenerate?
Your skin?
4. Briefly describe the method used to regenerate parts larger then 1 cm.
5. Briefly describe the method used on donor organs, like the liver, to engineer them for patient use.
Now watch this video “Replacing Body Parts”: http://www.pbs.org/wgbh/nova/body/replacing-body-parts.html
And this video “Anthony Atala: Printing a Human Kidney”
III. Forensic Biotechnology
A. DNA Fingerprinting (Profiling)
Steps in DNA fingerprinting:
1. DNA is amplified using Polymerase Chain Reaction (PCR)
What does PCR create?
2. DNA is cut into fragments using restriction enzymes
a. Restriction enzymes – always cut DNA at certain
locations
b. In this example, where does this specific restriction
enzyme always cut?
3. DNA fragments are compared using gel electrophoresis
a. What two factors cause
DNA segments to separate
out on a gel?
4. Can then determine if samples are the same DNA or
different
Genetics (Chapter 11 & 12)
I.
Genetics
A. Father of Genetics: Gregor Mendel – Austrian monk living in Czech
Republic monastary (mid 1800’s)
- First to develop a set of principles that explain inheritance and
that inheritance of many genetic characteristics follows a few
simple rules.
B.
Mendel’s subjects: pea plants (Fig. 11.2 & 11.3)
C.
How to read a Punnett Square
1. What is the P generation?
2. What is the F1 generation?
3. What must Parents undergo to produce haploid gametes?
4. Phenotype
5. Genotype
6. Does genotype largely determine phenotype?
D.
Monohybrid (One-Trait) Crosses (Fig. 11.5 & 11.6)
1. Started with parent plant that produced yellow peas (YY) and one that produced
green peas (yy) and crossed fertilized them.
2. Their offspring (F1 generation) were all yellow (Yy).
3. Was the heritable factor green lost?
4. Crossed fertilized the F1 generation
5. Their offspring (F2 generation) were ¾ yellow and ¼ green (3:1 ratio)
6. Conclusions:
a. How many forms of genes (alleles) does each individual have for
each trait?
b. How does an individual get these genes (alleles)?
c. How many alleles for each trait does each gamete (sperm or egg) contain?
d. What must the alleles do in order to only have one allele for each trait
in each gamete?
e. How many alleles for each trait are present in the embryo when fertilization
occurs (the union of sperm and egg)?
7. Mendel’s Law of Separation: Pairs of alleles separate during gamete
(egg & sperm) formation (meiosis) and the fusion of gametes at fertilization
creates allele pairs again.
8. What do we call an allele when it masks the expression of the other allele?
9. What do we call an allele whose trait is being masked?
E.
Alleles on Homologous Chromosomes (Fig. 11.8)
1. Homozygous
2. Heterozygous
F.
More Monohybrid Crosses
Tall
Short
Sperm
Phenotypic ratio?
Eggs
F1 Generation
Genotypic ratio?
1. Now cross fertilize the F1 generation:
F1 Generation
X
Phenotypic ratio?
Genotypic ratio?
PP
pp
Phenotypic ratio?
F1 Generation
Genotypic ratio?
Now cross fertilize the F1 generation:
Phenotypic ratio?
Genotypic ratio?
G.
Dihybrid Two-Trait Crosses (Fig. 11.9)
1. Crossed homozygous smooth and yellow pea plants (SSYY) with
wrinkled and green pea plants (ssyy)
2. Offspring all were smooth and yellow (SsYy) = heterozygotes
3. Mendel wondered if the two traits (SY) or (sy) were transmitted from
parents to offspring as a package or if each trait was inherited
independently of the other.
4. So he crossed fertilized the F1 generation
5. The F2 generation exhibited 4 phenotypes in a ratio of 9:3:3:1
6. Conclusions:
a. Do all possible combinations of traits occur in the gametes?
b. Does each pair of traits separate independently of the other pairs?
7. Mendel’s Law of Independent Assortment: Each pair of alleles separates
independently of the other pairs during gamete formation (metaphase in
meiosis). The inheritance of one characteristic has no effect on the
inheritance of another.
F2 Generation
Tall &
Green pods
Short &
Yellow pods
F1 Generation
Phenotypic ratio?
Genotypic ratio?
Now cross fertilize the F1 generation:
F2 Generation
Phenotypic ratio?
Genotypic ratio?
P Generation
Round & Yellow peas
F1 Generation
Phenotypic ratio?
Genotypic ratio?
Now cross fertilize the F1 generation:
F2 Generation
Phenotypic ratio?
Genotypic ratio?
Wrinkled and Green peas
H. Human Disorders Controlled by a Single Gene
- These disorders show inheritance patterns that Mendel studied.
- Genes involved in these disorders are located on autosomes.
1. Autosomal Recessive Disorders
a. Ex. Deafness
Parents are heterozygous & are carriers of recessive allele
for disorder but are phenotypically normal.
Can they produce a child that exhibits the condition?
What is the probability of this happening?
b. Ex. Sickle-Cell Anemia: (Fig. 12.4a)
a. Hemoglobin (protein) in red blood cells carry oxygen
to body. Sickle shaped red blood cells have a
different form of hemoglobin, they clog vessels and
result in tissue damage.
b. Widely affects Africa. 1 in 500 African Americans
born in U.S. is homozygous. 1 in 10 African
Americans is heterozygous.
2. Autosomal Dominant Disorders (Fig. 12.4b)
a. Parent need only pass on a single allele for
offspring to suffer from condition.
b. Usually individuals with this disorder are
heterozygous (Hh) for the disorder. Those that
are homozygous for the disorder (HH) die
while still an embryo.
c. Shows that dominant allele is not always
‘better’ or more abundant than the recessive!
d. Ex. Huntington disease
I.
Mendel’s Principles and Human Inheritance
a. Mendel’s principles apply to the inheritance of some human traits, not all. Traits such as eye, hair, and skin
color do not follow Mendel’s principles.
b. Pedigrees are used to determine inheritance of characteristics that follow Mendel’s principles in humans.
(Fig. 12.5).
?
d
d
?
?
d
J. Mendel’s principles are not valid for all traits:
1. Incomplete Dominance
Heterozygote phenotype is intermediate between
either of the homozygous phenotypes.
a. Ex. Snapdragon flowers:
- R allele produces red
- r allele produces no pigment
- Rr produces?
2. Multiple Alleles, Codominance, & Blood Type
a. Multiple Alleles
- Each individual carries, at most, two different alleles
for a particular gene, however, more than two
possible alleles exist in population
- Ex. Human blood types (Table 11.3): there are 3
alleles for blood type A, B & O which can produce 4
phenotypes (A, B, O or AB)
- These letters refer to carbohydrates designated A &
B which may be found on surface of red blood cells.
A person’s red blood cells may be coated with one
substance or the other (type A or B), with both (type
AB), or with neither (type O). Matching compatible
blood groups is critical for blood transfusions. If
donor’s blood has foreign carbohydrate on surface of
cells, antibodies in recipient’s blood bind to the
foreign carb and causes clumping.
b. Codominance
What alleles are both dominant?
3.
Polygenic Inheritance (Fig. 11.12)
a. Most traits are controlled by many genes.
b. Height, weight, eye color, skin color are controlled by several
genes working together.
c. That’s why we see a range of specific traits and not only really tall
people and really short people, or only really dark and really light
characters.
d. Causes greater diversity!
II. Sex Chromosomes & Sex Linked Genes
A. Sex linked genes
1. Eye color in fruit flies
a. White eye color is a recessive trait whose gene is on the X
chromosome
b. Female can carry one allele for white eye and one for red allele on her
second X chromosome.
c. Male will be white eyed if only one of his chromosomes, his lone X
chromosome, carries an allele for white eyes
d. How would a female get white eyes?
2. Sex linked disorders in humans: hemophilia (failure of blood to clot
properly), Duchene muscular dystrophy, red-green color blindness
a. Is color blindness on the X or Y chromosome?
b. Is color blindness a dominant or recessive?
XN
c. Which child will be color blind?
XN
d. How would a daughter be color blind?
Xn
III. Genes & Environment
A. Effects of genes vary according to the environment in which
genes are expressed. An organism’s genotype and environment
interact to produce an organism’s phenotype.
Watch the online video “Epigenetics” and answer the
following questions:
http://www.pbs.org/wgbh/nova/sciencenow/3411/02.html
1. Using computer terms describe what one’s epigenome is compared to one’s genome.
2. What does our epigenome “tell” our cells to do?
3. Does age affect how similar the epigenomes of identical twins are? How so?
4. Describe what epigenetic therapy is and how it works and state what illness it is being used to treat.
5. Can we negatively alter our epigenomes and our children’s epigenomes? How so?