Reproduction – Unit 1 Review Package
Microscope Basics
Be prepared to label the following parts of a microscope:
Body Tube
Coarse Adjustment Knob
Fine adjustment Knob
Revolving nosepiece
Objective lenses (4x, 10x, 40x)
Arm
Stage
Stage Clips
Diaphram
Light source
Base
Focusing with a Microscope
 Plug in and turn on.
 Lower stage completely.
 Turn nosepiece to low objective.
 Raise stage with coarse objective until specimen is seen. (Big knob)
 Fine focus the specimen.
 Centre specimen in the field of view.
 Rotate nosepiece to medium power objective.
 Refocus with fine adjustment.
 Re-centre the specimen.
 Refocus with fine adjustment. (Be careful not to break the slide.)
 Adjust the condenser. (Light)
 Start over to look at another specimen.
Microscope History and Development
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The father of microscopy, Anton Van Leeuwenhoek of Holland (1632-1723).
Anton Van Leeuwenhoek was the first to see and describe bacteria
Robert Hooke: Hooke was the first person to use the word "cell" to identify
microscopic structures when he was describing cork.
Technological Advances in Microscopes
Compound Light Microscopes: use light, two lenses
Transmission Electron Microscope (TEM): uses electrons,
Scanning Electron Microscope (SEM): electrons reflected from surface, 3D image
Magnification
Magnification = Objective lens X Ocular lens
4x, 10x, 40x)
(10x)
The Cell – Need to know Basics
 Cells are the “building blocks” of the human body.
 Every part of your body – bones, skin, nerves, hair, and muscle – is made if cells.
 Different cells do different jobs and have different shapes and sizes.
 Cells contain smaller “insides” called organelles – all with different jobs.
Organelles
 The largest and most important organelle is the nucleus.
 The nucleus controls everything that happens inside the cell. (Like the cells brain.)
 All cells are surrounded by a protective layer called the cell membrane.
 The cell membrane is semi-permeable, which means that it lets some substances pass through it,
but not others.
 The rest of the cell is called cytoplasm. Cytoplasm is a liquid containing chemicals needed to
keep the cell alive as well as hold the floating parts of the cell together.
Animal Cell and Organelles
Importance of Cell Division
Have you ever wiped out on your skateboard or bike?
Imagine how terrible it would be if every scratch or flaw on your skin remained.
Cells come from pre-existing cells through the process of cell division.
Plant cell and orgnanelles:
Functions of Cell Division
 Healing and tissue repair.
 To increase the number of cells (therefore increase the size of the organism).
 To replace dead and worn out cells.
 To create life (in unicellular organisms such as bacteria, and multicellular organisms such as
humans).
Reproduction and Cell Division
 Organisms of all species reproduce. They may reproduce asexually or sexually.
 In asexual reproduction a single organism gives rise to offspring with identical genetic
information. Ex. the cells of the human body, other than those found in the male testes and
female ovaries and bacteria use asexual reproduction to produce offspring by the process of
mitosis.
 In sexual reproduction, genetic information from two cells is combined to produce a new
genetically unique organism. Usually, sexual reproduction occurs when two specialized sex
cells unite to form a fertilized egg called a zygote.
The cell cycle: Division phase and interphase
Division Phase: (PMAT)
 Prophase
 Metaphase
 Anaphase
 Telophase
Interphase - The cell is engaged in metabolic activity and performing its prepare for mitosis (the next
four phases that lead up to and include nuclear division).
Chromosomes are not clearly discerned in the nucleus, although a dark spot called the nucleolus may
be visible.
The cell prepares for cell division by duplicating its genetic material.
Mitosis
 Mitosis is nuclear division plus cytokinesis, and produces two identical daughter cells during
prophase, metaphase, anaphase, and telophase.
 Interphase is often included in discussions of mitosis, but interphase is technically not part of
mitosis.
Prophase
Chromatin in the nucleus begins to condense and becomes visible in the light microscope as
chromosomes.
The nucleolus disappears.
Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres.
Some fibers cross the cell to form the mitotic spindle.
Metaphase
Spindle fibers align the chromosomes along the middle of the cell nucleus.
This line is referred to as the metaphase plate.
This organization helps to ensure that in the next phase, when the chromosomes are separated, each
new nucleus will receive one copy of each chromosome.
Anaphase
The paired chromosomes separate and move to opposite sides of the cell.
The two halves move to opposite poles of the cell.
If anaphase proceeds correctly, each of the daughter cells will have a complete set of genetic
information
Telophase
Chromosomes arrive at opposite poles of the cell, and new membranes form around the daughter
nuclei.
The chromosomes disperse and are no longer visible under the light microscope.
The cytoplasm and organelles separate into roughly equal parts, and the two daughter cells are formed.
Cytokinesis
In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the
center of the cell contracts, pinching the cell membrane in the middle and forming two new daughter
cells.
Cell theory:
1. All living things are made up of one or more cells.
2. The cell is the functional unit of life.
3. All cells come from pre-existing cells.
Meiosis
The function of meiosis is to produce eggs and sperm for sexual reproduction. (sex cells)
1. Egg and sperm cells must have half the number of chromosomes as the parent cell so that when
put together they will have the same number of chromosomes as the parent cells. (23 vs. 46 in
our body cells.)
2. Egg and sperm cells are NOT genetically identical to the parent cell like you see in mitosis.
3. Although you may look more like one parent than the other, you receive the same amount of
genetic information from each.
4. Chromosomes similar in shape, length and gene arrangement are called homologous
chromosomes.
Summary of Meiosis
First, the genetic material must be replicated so that each daughter cell can be given the appropriate
amount of genetic information. This occurs in Interphase.
Second, the genetic material must be divided twice so that each of the four daughter cells gets a set of
information.
Interphase -> PMAT -> PMAT -> Interphase
Types of Asexual Reproduction
Binary Fission:
 Organism splits directly into 2 equal-sized offspring.
 Each with a copy of the parents genetics information.
Ex. Bacteria
Budding:
 Offspring begins as a small outgrowth from the parent.
 Bud eventually breaks off and becomes an organism of its own.
Ex. Yeast
Fragmentation:
 A new organism is formed from a part that breaks off the parent
Ex. Starfish
Spore Formation:
 Organism undergoes frequent cell division to produce many smaller identical cells called
SPORES.
Ex. Penicillin (mold)
Vegetative Reproduction:
 Produce “runners” that can develop into another plant with identical genetic information.
Ex. Strawberries
DNA
DNA: The Genetic Material
The chromosomes of all living organisms are composed of DNA = Deoxyribonucleic acid.
What does it do?
 Guides the repair of damaged cells.
 Describes how cells will respond to changes in their environment.
How is this information sent?
 Sent from DNA to organelles through chemical messengers.
DNA is made of phosphate, ribose, and nitrogen bases held in a long winding double helix.
1. The nitrogen bases: thymine (t), adenine (a), cytosine (c), and guanine (g) are the characters
(letters) of the genetic alphabet. The order they appear in is a code.
2. T-A always pair together
3. C-G always pair together
4. A sequence of 3 nitrogen bases from a genetic code (word) that determines characteristics. (hair
colour, skin colour…)
5. A sequence of codes form a gene (phrase) that can be read by the cell.
DNA Replication
 The genetic code is stored in the 6 billion nitrogen bases of DNA, arranged in about 100
000genes on the 46 human chromosomes.
 During interphase, DNA unzips in order to allow the cell to duplicate.
 During cell division, the duplicates separate so each cell gets a complete set of genetic
information.
 Humans have 46 chromosomes in 23 pairs.
DNA, Mutations, and Cancer
 Genes found on chromosomes can undergo changes called mutations that can cause diseases.
 Cancer is uncontrolled cell division. The oncogenes can become mutated and defective and
cells may quickly and repeatedly divide themselves.
 The mutations of oncogenes is caused by substances or energy called carcinogens.
Cloning
 Cloning is the process of forming identical genetic offspring from a single cell.
 It is a natural process that happens daily in nature when organisms produce exact duplicates of
themselves by asexual reproduction (binary fission, budding…).
 Cloning is referred to as asexual reproduction because the DNA originates from a single
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parent.
Dolly - In 1996, Dolly the sheep, a species much more complex than simple plants or bacteria,
was cloned. She was the first fertile clone!
Reproduction in Flower Plants
Plant sex organs are very different than humans.
Male Sex Organs:
Pollen – male sex cells
Stamen:
 anther, where pollen is produced.
 - Filament, holds anther away from plant.
Female Sex Organs:
Eggs – female sex cells
Pistil – Sticky surface for the pollen to land on.
 Style – travelling chamber from stigma and ovary.
 Ovary – holds the egg.
Pollination
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The process by which pollen moves from an anther to the stigma so pollen can fertilize the egg.
Can occur between plants or in the same plant.
Wind, gravity, insects, animals, and water can carry pollen.
It is beneficial for pollen to be spread over large areas for greater genetic disbursement.
Fertilization
 The combining of pollen and eggs to produce a zygote.
 In plants , the zygote is better known as seeds.
 In some plants the ovary enlarges into fruit, therefore we are actually eating ovaries.
 Fruit is used for protection and disbursement ex. A bear eats berries and leaves seeds through its
droppings.