Transcript asexual reproduction

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Mutation Detection: Answers
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2.
Original DNA sequence
GGC[TACGAGCTTCGAAATTTGCCGATC]CCA
mRNA:AUG – CUC – GAA – GCU – UUA – AAC – GGC – UAG
A.A.s MET – LEU – GLU – ALA - LEU – ASP – GLY – STOP
Identify the reading frame by transcribing the DNA &
identifying the start codon. Then group the codons in 3’s until
you reach the stop codon.
Mutant one: FRAMESHIFT the original reading frame is affected
GGCTACGAGCTTCGAAAATTTGCCGATCCCA…
UUU – AAA – CGG – CUA – GGG 
MET – LEU – GLU – ALA – PHE – LYS – ARG – LEU – GLY
Homework
1. Mutant 2: NONSENSE an internal stop codon is inserted
GGCTACGAGCTTCGAACTTTGCCGATCCCA
MET – LEU – GLU – ALA – STOP
2.
Mutant 3: MISSENSE a new amino acid is made with the mutation
GGCTACGAGCCTCGAAATTTGCCGATCCCA
MET – LEU – GLU – ALA – GLU  GLY
3.
Mutant 4: SILENT the gene isn’t affected as GAC & GAG both code for the
same amino acid GGCTACGACCTTCGAAATTTGCCGATCCCA
MET – LEU – GLU – ALA – LEU  LEU
Intro
 You all learned in MITOSIS that cells reproduce
through the process of cell division.
 This includes mitosis & cytokinesis
 The process creates 2 identical daughter cells,
also called clones for the reasons of replacing,
growing the # of, and repairing our body’s cells.
 In this lesson you are going to learn the
processes by which organisms reproduce.
 Next you’ll learn how gametes form… through
meiosis.
Common Sense
 “The chief function of the reproductive system is to
ensure survival of the species.”
 http://www.daviddarling.info/encyclopedia/R/reproductive_system.html
 You all should know by now that, for humans, it
takes a mom and a dad to produce a baby through
the mechanism of sex.
 But questions we must answer:
1. Is this the only way organisms reproduce?
2. How do each of the methods that satisfy the need
to reproduce work? (in general)
3. Why do the methods work?
4. What are the advantages and disadvantages?
Objectives. Organism Reproduction
 Compare the genetics of offspring in asexual
reproduction with the parent.
 Describe how the offspring in sexual reproduction
compare genetically with the parent.
 Chromosome Number Objectives:
 Explain why chromosomes are important to an organism.
 Compare the number of sets of chromosomes between a
haploid cell and a diploid cell.
 Create a karyotype to determine chromosome number.
Vocabulary
 Gamete
 Zygote
 Diploid
 Haploid
 Homologous chromosome
Asexual Reproduction
 In asexual reproduction (like MITOSIS) a
single parent passes a complete copy of
its genetic information to each of its
offspring.
 The offspring formed by asexual
reproduction are genetically identical to
its parent.
 Clones…
 Asexual reproduction is broken down into 4 types:
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Binary fission
Fragmentation
Budding
Parthenogenesis
Asexual Reproduction
 Prokaryotes reproduce
asexually by a kind of cell
division called binary
fission.
 Similar to MITOSIS
without the nucleus.
 One parent bacteria
 Many unicellular
eukaryotes also
reproduce asexually.
 Does anyone know of a
unicellular eukaryote?
 Amoeba…for example
Asexual Reproduction
 Some multicellular eukaryotes,
such as starfish or Planarian, go
through fragmentation.
 Fragmentation is a kind of
asexual reproduction in which
the body breaks into several
pieces.
 Some or all of these fragments re-
grow missing parts and develop into
complete adults.
 Does anyone know what the regrowth of a lost appendage is
called?
 Regeneration
Asexual Reproduction
 Other animals, such as the hydra,
go through budding. In budding,
new individuals split off from
existing ones.
 Some plants, such as potatoes,
can form whole new plants from
parts of stems.
 The knots found on old potatoes are
called buds
 Other plants can reproduce from
roots or leaves.
Asexual
Reproduction
 Many species have been
reported to have the ability to
reproduce by
parthenogenesis.
 Parthenogenesis is a process in
which a female makes a viable
egg that grows into an adult
without being fertilized by a
male.
 Ex.
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Aphids (pictured)
Water fleas
Boas
Komodo dragons
Sharks
Others.
Check for Understanding
 What are 4 types of asexual reproduction we discussed so
far?
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1. binary fission
2. fragmentation
3. budding
4. parthenogenesis
 List the appropriate definition next to the word
 A. a viable egg produced by the mother that grows into an adult
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without fertilization
B. new individuals split off from existing ones
C. body breaks into several pieces
D. reproduction through cell division
Answers: d, c, b, a
Sexual Reproduction
Multicellular Organisms have two types of cells.
Germ Cells and Somatic Cells
 Our body cells are called somatic cells.
 These are the major types of cells that form organisms: skin cells,
muscle cells, nerve cells, etc.
 These grow in number (proliferate) through MITOSIS.
 Somatic cells do not participate in sexual reproduction.
 Cells that are created for sexual reproduction are called
germ cells.
 These undergo MEIOSIS division to create gametes.
 Examples: Sperm, egg, pollen, spores
 Only germ cells can produce gametes.
Sexual Reproduction
 Most eukaryotic organisms reproduce sexually.
 In sexual reproduction, gametes from genetically different
parents produce offspring that are a genetic hybrid of the
parents.
 Each parent produces a reproductive cell, called a gamete.
 Male Gamete = sperm
 Female Gamete = egg
 Gametes fuse during fertilization to form a zygote.
 The zygote develops through mitosis into an embryo.
 Because both parents give genetic material, the offspring
has traits of both parents but is not exactly like either parent.
•Asexual
•Genetically identical
•Sexual
•Genetically varied
Germ cell
Meiosis
Parent
Gametes
•Cellular reproduction: MITOSIS
•Binary fission
•Fragmentation
•Budding
•Parthenogenesis
Fertilization
Offspring
Zygote
Reproduction
 We have learned the two types of
reproduction.
 They are:
 1. Asexual
 2. Sexual
 How do the offspring produced from each of
these types of reproduction compare to its
parent?
 Asexual = they are genetically identical
 Sexual = they are genetically different (but
express traits from both parents)
Asexual Reproduction
Advantages of Asexual
Reproduction (cloning)
Disadvantages of Asexual
Reproduction
Asexual reproduction is the
No genetic diversity means they
simplest, most efficient method cannot rapidly adapt in a
of reproduction.
changing environment.
Asexual reproduction allows
organisms to produce many
offspring in a short period of
time without using energy to
make gametes or to find a mate.
The downside is that the genetic
material of these organisms
varies little between individuals,
so they may be at a
disadvantage in a changing
environment.
Sexual Reproduction
Advantages of Sexual
Reproduction
Disadvantages of Sexual
Reproduction
Sexual reproduction produces
genetically diverse individuals.
Takes WAY more energy.
A population of diverse
organisms with some variability
is more likely to have some
individuals that survive a major
environmental change.
This is the advantage, the
benefit, of sexual reproduction.
Think of how much energy it
takes to find and keep a
girlfriend/boyfriend.
Recap
 To highlight the benefits of each restate.
 The benefits of asexual reproduction are…
 Saves time & energy
 The benefits of sexual reproduction are…
 Genetic diversity.
Why is Genetic Variability A
Benefit?
 Sexual reproduction is only beneficial if it
creates a wide variety of traits in offspring.
 If every pregnancy yielded clones there would be no
point to it.
 Within every population, due to numerous
environmental pressures that have gone on
throughout its history, there exists numerous
versions of each thing that can be produced.
 This is fundamental in Natural Selection &
Evolution.
The Benefit of Diversity
 EX: Variation in eye color provides different benefits.
 Eye color has a direct correlation to absorbing sunlight or being able to
see in the dark better.
 Light eyes can see better in the dark, dark eyes have less glare in the sun.
 EX: Variation in skin color provides different benefits.
 Skin color changes the overall affect of UV radiation due to melanin
absorption.
 Dark skin converts UV radiation into heat, light skin has higher frequency
of skin cancer but can tan to accommodate extra sunlight.
[The photochemical properties of melanin make it an excellent photoprotectant. It absorbs harmful UVradiation and transforms the energy into harmless heat through a process called "ultrafast internal
conversion".] This property enables melanin to dissipate more than 99.9% of the absorbed UV radiation
as heat[3]
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Where there’s more sunlight then the skin colors are generally, historically darker.
The Benefits of Genetic Variability
•Each version of the gene has advantages in some
circumstances, disadvantages in others.
Trait: Skin color
In sunny climate
No
Yes
No
Okay
Yes
Yes
In low-sun climate
Yes
No
Yes
Okay
No
No
In sunny climate
No
No
No
Yes
Yes
Yes
In low-sun climate
Yes
Yes
Yes
No
No
No
Trait: Eye Color
What does this mean?
 Having two parents that are genetically different creating a
genetically different offspring allows for several ways to
keep genetic diversity evolving, and this is a good thing.
 1st: New combinations from parents with different genes
allow for new, maybe unseen traits to be created.
 2nd: Because we carry two copies of each gene, sometimes a
trait that is bad right now will be kept in the gene pool,
hidden by a more dominant form. Sometimes these traits
turn out to be good later on down the road.
 3rd: If the environment suddenly changes, the estimate is
10% of the human population contains the trait necessary to
survive almost any biologically significant event.
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Viral or bacterial infection resistance.
Metabolic stress = lack of food/water.
Changes in O2 levels.
Changes in amounts of sunlight.
Temperature fluctuations.
In Summary. Genetic
Variation from Sexual
Reproduction.
 Mixing versions of genes does several things.
 It hides bad recessive genes behind good dominant genes.
 Having multiple versions of a gene allows for a population to
respond to changes.
Part II Chromosome Number
 Organisms can be organized by how they
reproduce.
 When an organism reproduces the same way
as another an alternative way has been
discovered to tell the difference between
organisms.
 It has to do with the number of their
chromosomes.
Chromosomes
 Each species has a specific arrangement of
chromosomes, both numbers and sizes.
 Recall that a chromosome is a huge continuous
molecule of DNA & Each chromosome, for each
organism, has thousands of genes that play an
important role in determining how an organism
develops and functions.
 Some genes are unique to the organism, but often many
are very similar as variations of an original.
 Plus, an organism must have exactly the same
number of chromosomes as other members of the
species.
 If an organism has too many or too few chromosomes, the
organism may not develop and function properly.
 On top of that, organisms must have the same number of
chromosomes to mate effectively. (discussed more in
ecology)
Chromosome Number of Various
Organisms
Visual Concepts: Chromosome
Number
Click above to play the video.
Chromosome
Number
 Every organism has a
specific number of
chromosomes and sets.
 The number of
chromosomes can be
determined by
observing the
karyotype of the
organism
What is ‘n’?
 The number of chromosomes in an
organism or cell is determined by
inheritance patterns.
 ‘n’ = the number of chromosomes in
one set.
 Ex. Humans have 23 chromosomes in one set.
 Each parent contributes one set so humans have 2 sets
of 23, for a total 46 chromosomes.
 ‘n’ in the case is 23.
Decide
 Here we have a
karyotype from a
human.
 How many
chromosomes are
there?
 How many sets?
 How many in one
set?
 Human gametes have 23 chromosomes in their sets, so for
humans n = 23.
Chromosome Number
Haploid and Diploid Cells
 If a cell has one set of chromosomes it’s considered haploid.
 Describes a cell, nucleus, or organism that has only one set of unpaired
chromosomes
 A cell, such as a somatic cell, that has two sets of chromosomes
is diploid.
 A cell that contains 2 haploid sets of chromosomes
 There does exist a third kind, polyploid, which can have many
more than two copies of each chromosome.
Polyploid types are labeled according to the number of chromosome sets in the nucleus:
triploid (three sets; 3x), for example the phylum Tardigrada[3]
tetraploid (four sets; 4x), for example Salmonidae fish
pentaploid (five sets; 5x), for example
hexaploid (six sets; 6x), for example wheat, kiwifruit[4]
octaploid (eight sets; 8x), for example Acipenser (genus of sturgeon fish)
decaploid (ten sets; 10x), for example certain strawberries
dodecaploid (twelve sets; 12x), for example the plant Celosia argentea and the amphibian Xenopus ruwenzoriensis
Chromosome Number
Haploid and Diploid Cells
 In organisms that reproduce with two parents there are
two types of cells.
 Somatic Cells are also called body cells. These are cells
that make up an organism.
 Examples: Skin, muscle, brain, blood, etc.
 Somatic cells are diploid (in humans)
 Gamete Cells are also called reproduction cells. These are
cells that are used in sexual reproduction.
 Examples: Sperm, egg, pollen
 Gametes are haploid cells.
Chromosome Types
Homologous Chromosomes
 Each diploid cell has pairs of chromosomes
made up of two homologous chromosomes.
 Homologous chromosomes are chromosomes
that are similar in size, in shape, and in kinds of
genes.
 Each chromosome in a homologous pair comes
from one of the two parents.
 Homologous chromosomes can carry different
forms of the same genes.
 Mom may have the black hair gene where dad could
have blond.
•The same
genes but
usually
different
versions.
Chromosome Types
Autosomes and Sex Chromosomes
 In a nucleus, there are two types of chromosomes.
 Autosomes are chromosomes with genes that do not
determine the sex of an individual.
 What are these genes?
 Sex chromosomes have genes that determine the sex of
an individual.
Chromosome Types
Autosomes and Sex Chromosomes
 In humans and many other organisms, the two sex
chromosomes are referred to as the X and Y
chromosomes.
 The genes that cause a zygote to develop into a male are
located on the Y chromosome.
 Human males have one X chromosome and one Y
chromosome (XY),
 and human females have two X chromosomes (XX).
Summary
 Tell me:
 What are the 4 types of asexual reproduction?
 As a result of asexual reproduction, how do offspring
compare to their parents?
 How do offspring of sexual reproduction compare to
their parents?
 What does haploid mean?
 What does diploid mean?
Summary
 This is a karyotype.
 Tell me what
homologous
chromosomes are.
 Does this show a
haploid or diploid
organism?
 What is this individual’s
haploid number?
 n=?
 What is this individual’s
diploid number?
 2n = ?
What’s Next?
 Now that you have the necessary information
you will begin to explore the process of meiosis.
 You will have these assignments to help you
practice with it.
 Today: Meiosis Notes. Read and Research the steps
and highlights of meiosis in groups.
 By Monday: Complete the Meiosis Web Lesson.
 Pay really close attention to the web lesson. Go through
it several times to completely understand it.
 By Monday: Have read and outlined CH10
Karyotyping.
 Today you will create and analyze a
karyotype, one tool doctors & scientists use
to determine ploidy number in an organism.
 A karyotype can also be used as a pre-natal
diagnostic tool to determine & predict
abnormal births.