Name: ______________________________________
Unit 6: Asexual & Sexual Reproduction
Part A: Cells


cell theory
cell division
Per. ________
Part E: Meiosis

Part B: Asexual Reproduction

Asexual Reproduction
o Binary fission
ex.
o Budding
ex.
o Spore Formation
ex.
o Regeneration
ex.
o Vegetative Propagation
ex.

Sexual Reproduction
o Sex cells (gametes): egg & sperm
o Fertilization
 zygote
o Homologous Chromosomes
 haploid/ diploid/ monoploid/ n/ 2n
Meiosis = reduction division
o Significance of meiosis
o synapsis / tetrad formation
o gametogenesis
o spermatogenesis
o oogenesis
 polar bodies
Part C: Chromosomes









chromatin
chromosome
histone
chromatid
centromere
autosomes
Karyotype
diploid
haploid
Part D: Mitosis






cell division
Interphase
Phase of mitosis
o Prophase
 chromosomes
 centrioles/asters
 spindle fibers
o Metaphase
 equator
 traction fibers
o Anaphase
o Telophase
 cleavage furrow
 cell plate
 daughter cells
Cytokinesis
Differences between plant and animal mitosis
cancer
1
Part A: Cells
Cell Theory

All living things are made of cells

Cells are the basic unit of life

All cells arise from pre-exisiting cells
Cell Division



Cells produce new cells through the process of cell division
Cell division different in prokaryotes and eukaryotes
Some tissues are repaired more often than others
o ex: WBC’s (white blood cells); skin cells; gut; embryonic cells
o cells that don’t divide after birth: RBC’s (red blood cells); nerve cells; brain cells
Reason for Cell Division

Cell growth

Repair & replacement of damaged cells

Reproduction of species
Types of Reproduction

Asexual reproduction

Sexual reproduction
Part B: Asexual Reproduction

type of reproduction that involves 1 parent



offspring is genetically IDENTICAL to the parent
more common in invertebrate animals than in vertebrate animals
unicellular & multicellular plants can reproduce both asexually & sexually

Cloning - offspring from a single body cell of a parent
Types of Asexual Reproduction:
1. binary fission
-simplest type of asexual reproduction
-cell splits in half
-daughter cells equal in size
-ex. amoeba, algae, bacteria, protozoa
2. budding
= growth of small reproductive fragment from parent.
-unequal cell division
ex. yeast, hydra
3. sporulation
-multiple asexual reproductive cells released from parent
ex. ferns, mosses, fungi
2
4. regeneration
-new organism develop from part of the parent
-replacement of lost body parts
ex. planaria, sponges, starfish, lobster claw
5. vegetative propagation
-asexual reproduction from parts of plant
o runners: strawberries
o tubers: potatoes
o bulbs: onions
o rhizomes: iris
o cutting: aloe
o grafting: similar plants
Label the following diagrams of types of asexual reproduction as binary fission, budding, sporulation, regeneration,
or vegetative propagation. Give two examples of organisms that use each method of reproduction.
1.
2.
3.
Type: binary fission
Type: sporulation
Type: budding
Examples: amoeba
Examples: fungi
Examples: yeast
bacteria
mosses
4.
hydra
5.
Type: vegatative propagation
Type: regeneration
Examples: strawberries
Examples: starfish
Potatoes
planaria
3
Practice Questions
______ 1. Which method of reproduction is shown in the diagram at the right?
1. stem cutting
3. tuber formation
2. budding
4. sporulation
___1__ 2. Which diagram represents binary fission?
sporulation 3. The diagram at the right includes information on asexual reproduction. Which term belongs in the
area labeled X?
Types of
Asexual
Reproduction
Binary
Fission
Budding
Amoeba
Hydra
X
Bread
Mold
Vegetative
Propagation
Potato
______ 4. Which phrase best describes the process represented in the diagram below?
1. germination of a pollen grain in a flower
2. identical gametes being formed by mitotic cell division
3. development f seeds in an ovule
4. daughter cells being formed by mitotic cell division
______ 5. In certain plants, roots will develop from a stem cutting. This type of reproduction is known as
1. vegetative propagation
2. binary fission
3. unicellular budding
3. spore formation
______ 6. One way to produce large numbers of genetically identical offspring is by
1. cloning
3. changing genes by agents such as radiation or chemicals
2. fertilization
4. inserting a DNA segment into a different DNA molecule
______ 7. Potatoes, strawberries, and seedless oranges are generally produced by an asexual means of
reproduction known as
1. sporulation
2. budding
3. binary fission
4. vegetative propagation
4
Part C: Chromosomes

most of the time, genetic material is spread out into long,
thin strands called chromatin

when cell division starts, chromatin condenses to form
chromosome
o
rod-shaped structures made of DNA tightly coiled
around proteins called histones

in cells preparing to divide, DNA has been duplicated to
produce two identical chromatids

chromatids are joined at the centromere
Chromosomes numbers are constant within a species:
o dog
78
o lettuce
o fruit fly
8
o gorilla
o human
46
o soybean
18
48
40
o
o
o
potato
48
camel
70
guinea pig 64
Types of Chromosomes
1. sex chromosomes: one pair of chromosomes that determine gender
ex. humans
female= XX
male= XY
2. autosomes: all of the remaining non-sex chromosomes
ex.- 22 pairs of chromosomes having the same shape and carrying the same kinds of traits
- one autosome is inherited from each parent
karyotype = Photomicrograph of chromosomes in a
dividing cell.
In every cell but sex cells, there are distinct numbers of pairs of chromosomes:
ex. during normal cell division:
This number, which is typical of the species, is the diploid number (2n)
During sex formation, this number is halved and is called the haploid (n) number
Why is this necessary? If reproducing cells were diploid, then the new organism would have too many
chromosomes.
5
Part D: Mitosis
Cell Division


in prokaryotes = binary fission is the division of the cell into two new daughter cells
o each daughter cell has exactly the same kind and amount of DNA as the original cell had
in eukaryotes = mitosis and/or meiosis (reduction division)
Cell Cycle

sequence of events in cell division:
o Interphase
o Mitosis
o Cytokinesis
Interphase


resting stage
cell spend most of their time in this phase (up to 90%)


chromosomes not visible- in form of chromatin
cell prepares for division
o G1: cell grows
o S (synthesis): DNA is copied
o G2: cell prepares to divide
Mitosis (M Phase)


division of nucleus
duplicated DNA evenly distributed to two daughter cells
1) Prophase




2)



chromatin thickens and shortens into chromosome (now visible)
centrioles migrate to opposite poles
spindle fibers form
nuclear membrane disappears
Metaphase
chromosomes line up at middle of cell
centromeres divide; chromatids separate
chromosomes easiest to identify in this phase
3) Anaphase
 chromatids (daughter chromosomes) move to opposite poles of the dividing cell
 pulled by traction fibers attached to centromeres
4)



Telophase
spindle disappears
chromosomes become chromatin
nuclear membranes reform
Remember… People Meet
6
And Talk
Cytokinesis

division of cytoplasm
Cancer




mitosis controlled by proteins produced by oncogenes
mutation in these proteins causes cancer
abnormal cell growth causes tumors
o benign: mass of “normal” cells
o malignant: mass of cancerous cells
metastasis- spread of cancer cells beyond their original site
Fill in each box.
centrioles
chromatin
interphase
prophase
spindle fibers
metaphase
anaphase
telophase
cytokinesis
10.
11.
12.
13.
14.
15.
In humans, each cell (except sex cells) has how many chromosomes? 46
After mitosis, how many daughter cells are produced? 2
After mitosis (in a human cell), each daughter cell has how many chromosomes? 46
How many phases are in MITOSIS? 4 (Prophase, Metaphse, Anaphase, Telophase)
Which phase of the cell cycle is the longest? interphase
During which phase does cytokinesis begin? telophase
7
The diagram below shows six cells in various phases of the cell cycle. Note the cells are not arranged in the
order in which mitosis occurs and one of the phases of mitosis occurs twice. Use the diagram to answer
questions 1-7.
1) Cells A and F show an early and a late stage of the same phase of mitosis. What phase is it? prophase
2) Which cell is in metaphase? C
3) Which cell is in the first phase of mitosis? A
4) In cell A, what structure is labeled X? centrioles
5) Which cell is in the “in between” phase of mitosis? interphase
6) Place the diagrams in order from first to last. D  A  F  C  E  B
7) Are the cells depicted plant or animal cells? Explain your answer. animal cells; they’re round and have
centrioles.
8) What is the longest phase of the cell cycle? interphase
9) Why is mitosis important? growth & repair
Practice Questions
_____ 1. Which process is represented by the photographs below?
1. mitotic cell division
3. internal fertilization
2. zygote formation
4. segregation and recombination
_____ 2. The diagrams below represent stages of a cellular process.
1. A B CD
2. B D C A
3. C B D A
_____ 3. Normal mitotic cell division results in each daughter cell having
1. half the number of chromosomes as the parent cell
2. the same number and kinds of chromosomes as the parent cell
3. the same number but different kinds of chromosomes as the parent cell
4. twice the number of chromosomes as the parent cell
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4. D B A C
_____ 4. Which statement best describes the process of asexual reproduction?
1. It involves two parents.
3. It results in variation in offspring.
2. It occurs without the fusion of nuclei.
4. It involves the production of gametes.
_____ 5. A photomicrograph of cells involved in various stages of nuclear division is shown at
the right. Which title is most appropriate for this photomicrograph?
1. Mitosis in an Onion Root Tip
2. Cell Division in Human Blood Cells
3. Meiosis in Male Gametes
4. Gametogenesis in Yeast Cells
_____ 6. Which would most likely result if mitosis was not accompanied by cytoplasmic division?
1. two cells, each with one nucleus
3. one cell with two identical nuclei
2. two cells, each without a nucleus
4. one cell without a nucleus
_____ 7. The diagram illustrates the process of cell division.
What is the significance of anaphase in this process?
1. Anaphase usually ensures that each daughter cell has the same number of chromosomes as the parent cell.
2. Anaphase usually ensures that each daughter cell has twice as many chromosomes as the parent cell.
3. In anaphase, the cell splits in half.
4. In anaphase, the DNA is being replicated.
haploid
haploid
egg
sperm
diploid
Part E: Meiosis
Sexual Reproduction



two parents
genetically different offspring
fusion of two gametes (sex cells)
zygote
= fertilization
egg + sperm = zygote
23 + 23
= 46
value of variation is to allow species to adapt rapidly to new conditions
o

Egg and Sperm Production
= gametogenesis
1. spermatogenesis
= development of 4 sperm from each spermatogonial cell
2. oogenesis
= development of 1 egg and 3 polar bodies from each oogonial cell
Why? Unequal sharing of cytoplasm during cell division
Fertilization



restores diploid (2n) number of chromosomes
one homologous chromosome comes from each parent
voila! Variety!!
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Meiosis

cell division producing 4 cells with half the number of chromosomes (sperm & egg only)

normal chromosome number restored at fertilization
Meiosis I


in interphase I, DNA replicates
in prophase I chromosomes become visible, homologous chromosomes synapse (coming
together) forming a tetrad


in metaphase I, tetrads move to center of cell
crossing-over may occur at this point (exchange of chromosomal segments)
o allows genetic recombination

anaphase I results in homologous chromosomes separating and moving to opposite poles of cell
(chromatids do not separate)
telophase I results in two daughter cells that are haploid
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Meiosis II



no replication
prophase II- short or absent
metaphase II- chromosomes to center of cell

anaphase II- chromatids separate and move to poles

telophase II- 4 cells form (haploid)

nondisjunction- failure of chromosomes to separate during meiosis
11
12
Phases of Meiosis
Name of Phase
Description
1. prophase I
Homologous chromosomes pair up and form tetrad
2. anaphase I
Spindle fibers move homologous chromosomes to opposite sides
3. telophase II
Nuclear membrane reforms, cytoplasm divides, 4 daughter cells formed
4. metaphase II
Chromosomes line up along equator, not in homologous pairs
5. metaphase I
Crossing-over occurs
6. anaphase II
Chromatids separate
7. metaphase I
Homologs line up alone equator
8. telophase I
Cytoplasm divides, 2 daughter cells are formed
anaphase I
metaphase I
prophase II
anaphase II
metaphase II
prophase I
telophase I
telophase II
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Meiosis
On each of the images, label the phase of meiosis
1. anaphase II
4. telophase II
7. metaphase II
14
2. cytokinesis I
3. metaphase I
5. telophase I
6. cytokinesis II
8. prophase I
9. prophase II
10. anaphase I
11. A cell with a diploid number of 20 undergoes meiosis. This will produce
4 daughter cells, each with 10 chromosomes.
12. Synapsis occurs during this phase: prophase I
13. Tetrads line up along the equator during this phase: metaphase I
14. At the end of meiosis I, 2 daughter cells are created. These daughter
cells are [ diploid | haploid ].
15. Meiosis occurs in what type of cells: gametes (sex cells)
1. Each body cell of a chimpanzee contains 48 chromosomes. How many chromosomes would normally be present in
a gamete produced by this chimpanzee?
1. 24
2. 36
3. 48
4. 96
_____2. The diagram shows a sequence of events
. Which processes are indicated by letters A and B?
1. meiotic cell division and fertilization
2. mitotic cell division and fertilization
3. meiotic cell division and cleavage
4. mitotic cell division and cleavage
_____3. In animals that reproduce sexually, which is the correct sequence for the development of a new organism?
1. gametes – zygote – fertilization – embryo
3. zygote – gametes – fertilization – embryo
2. fertilization – zygote – gametes – embryo
4. gametes – fertilization – zygote – embryo
_____4. Which diagram best represents part of the process of sperm formation in an organism that has a normal
chromosome number of eight?
1.
2.
3.
_____5. The diagram below shows a process that can occur during meiosis.
4.
The most likely result of this process is
1. a new combination of inheritable traits that can appear in the offspring
2. an inability to pass either of these chromosomes on to offspring
3. a loss of genetic information that will produce a genetic disorder in the offspring
4. an increase in the chromosome number of the organism in which this process occurs
Mitosis and Meiosis Worksheet
15
I.
Draw the chromosomes in the cell as it undergoes Mitosis:
a
a
A
b
A
B
b
B
Prophase
Metaphase
Anaphase
Telophase
Daughter Cells
II.
Draw the chromosomes in the cell as it undergoes Meiosis (same parent cell):
Prophase I
Metaphase I
Anaphase II
Telophase II
Comparing Mitosis & Meiosis
16
Anaphase I
Metaphase II
Telophase I
Prophase II
Daughter
Cells
Meiosis
Mitosis
# of cells made
4
2
# of cell divisions
2
1
chromosome #
haploid (n)
diploid (2n)
cell type
gametes
body cells
function
sexual reproduction
growth & repair
Practice Questions
_____1. The members of a certain species of grass in a lawn are genetically identical. The best explanation for this
observation is that the species most probably reproduces
1. by an asexual method
3. after pollination by a particular species of bee
2. after pollination by the wind
4. by identical sperm fertilizing the eggs
_____2. In humans, which cell is produced most directly by mitotic cell division?
1. a sperm cell
2. a skin cell
3. an egg cell
4. a zygote
_____3. The diagram shows a sequence of events.
The sequence of events from rabbits to zygote is known as
1. sexual reproduction
2. fission
3. sporulation
4. vegetative propagation
_____4. Complex organisms produce sex cells that unite during fertilization, forming a single cell known as
1. an embryo
2. a gamete
3. a gonad
4. a zygote
_____5. A cell with a diploid chromosome number of 12 divided two times, producing four cells with six
chromosomes each. The process that produced these four cells was most likely
1. internal fertilization 2. external fertilization
3. mitotic cell division
4. meiotic cell division
_____6. Which phrase best describes the process represented in the diagram?
1.
2.
3.
4.
germination of a pollen grain in a flower
identical gametes being formed by mitotic cell division
development of seeds in a ovule
daughter cells being formed by mitotic cell division
17
_____7. A colony of red bacteria is allowed to reproduce for 16 generations. A scientist examines the colony at
the end of this time and notes that all the individuals are almost identical in all characteristics. This evidence
suggests that the bacteria
1. did not receive the proper nutrients
3. exchanged genetic material
2. reproduced sexually
4. reproduced asexually
_____8. Which statement best explains the significance of meiosis in the evolution of a species?
1. Meiosis produces eggs and sperm that are alike.
2. Meiosis provides for chromosomal variation in the gametes produced by an organism.
3. Equal numbers of eggs and sperm are produced by meiosis.
4. The gametes produced by meiosis ensure the continuation of any particular species by asexual reproduction.
_____9. The diagrams represent some events in a cell undergoing normal meiotic cell division.
Which diagram below most likely represents a new cell resulting from meiotic cell division of the cell?
1.
2.
3.
4.
_____10. One way to produce large numbers of genetically identical offspring is by
1. cloning
3. changing genes by agents such as radiation or chemicals
2. fertilization
4. inserting a DNA segment into a different DNA molecule
_____11.
How does the type of reproduction shown in method A in the diagram differ from the type of reproduction shown
in method B ?
1. Method A illustrates sexual reproduction, and method B illustrates asexual reproduction.
2. Offspring produced by method B will be genetically alike, but offspring produced by method A will be
genetically different.
3. The two cells shown in the last step of method A are genetically alike, but the two cells shown in the last
step of method B are genetically different.
4. Offspring produced by method A will be genetically like the parent, but offspring produced by method B
will be genetically different from the parents.
_____12. The nucleus is removed from a body cell of one organism and is placed in an egg cell that has had its
nucleus removed. This process, which results in the production of organisms that are genetically alike, is known as
1. cloning
2. fertilization
3. biological adaptation
4. DNA production
18
_____13. Most cells in the body of a fruit fly contain eight chromosomes. In some cells, only four chromosomes are
present, a condition which is a direct result of
1. mitotic cell division
2. meiotic cell division
3. embryonic differentiation 4. internal fertilization
_____14. The chromosome content of a skin cell that is about to form two new skin cells is represented in the
diagram.
Which diagram below best represents the chromosomes that would be found in the two new skin cells produced as a
result of this process?
1.
3.
2.
4.
_____15. Strawberries can reproduce by means of runners, which are stems that grow horizontally along the
ground. At the region of the runner that touches the ground, a new plant develops. The new plant is genetically
identical to the parent because
1. it was produced sexually
2. nuclei traveled to the new plant through the runner to fertilize it
3. it was produced asexually
4. there were no other strawberry plants in the area to provide fertilization
_____16. Which statement is true of both mitosis and meiosis?
1. Both are involved in asexual reproduction.
3. The number of chromosomes is reduced by half.
2. Both occur only in reproductive cells.
4. DNA replication occurs before the division of the nucleus.
_____17. Meiosis and fertilization are important for the survival of many species because these two processes
result in
1. large numbers of gametes
3. cloning of superior offspring
2. increasingly complex multicellular organisms 4. genetic variability of offspring
_____18. The least genetic variation will probably be found in the offspring of organisms that reproduce using
1. mitosis to produce a larger population
2. meiosis to produce gametes
3. fusion of eggs and sperm to produce zygotes
4. internal fertilization to produce an embryo
19
_____19. Which row in the chart below best describes asexual reproduction?
Number of
Parents
Comparison of
Offspring to
Parents
1.
one
identical
2.
one
different
3.
two
identical
4.
two
different
Row
_____20. Marine sponges contain a biological catalyst that blocks a certain step in the separation of chromosomes.
Which cellular process would be directly affected by this catalyst?
1. mitosis
2. diffusion
3. respiration
4. photosynthesis
_____21. Which two structures of a frog would most likely have the same chromosome number?
1. skin cell and fertilized egg cell
3. kidney cell and egg cell
2. zygote and sperm cell
4. liver cell and sperm cell
_____22.
The diagram to the left represents a nucleus containing the normal chromosome number for a species.
Which diagram below bests illustrates the normal formation of a cell that contains all of the genetic information
needed for growth, development, and future reproduction of this species?
1.
2.
3.
4.
_____23. Which statement best explains the significance of meiosis in the process of evolution within species?
1.
2.
3.
4.
20
The gametes produced by meiosis ensure the continuation of any particular species by asexual reproduction.
Equal numbers of eggs and sperm are produced by meiosis.
Meiosis produces eggs and sperm that are alike.
Meiosis provides for variation in the gametes produced by an organism.
21