SNC2D1

2022-2023

Plant and Animal Cells

- Cells are the smallest unit of life
- Plant and animal cells contain membrane-bound organelles.
- An organelle is a specific structure that carries out a specific function.

Prokaryotic Cells: Very small and do not contain membrane bound organelles (ca n’t see them
with a light microscope) - Example: Bacteria

Eukaryotic - Larger, containing membrane bound organelles. Example: Plant and Animal Cells

Cell Theory
1. All living things are made of cells
2. All cells came from pre-existing cells
3. The cell is the smallest functional unit (basic building block) of living things

Surface Area Volume Ratio

- Most cells are relatively small because as size increases, volume increases much more
rapidly
- Longer diffusion time

Microscopes
- Compound light microscopes
- Magnify in stages using multiple lenses
- Transmission electron microscopes
- Electrons transmitted through specimen
- Gives a 2D image magnified 1,00,000x
- Scanning electron microscope
- Electrons beamed onto surface of the specimen

Organelles
 Organelle Function Plant/Animal Cell or
Both
Nucleus - Controls the cell's activities
- Contains DNA
- Surrounded by nuclear membrane envelope with nuclear pores

Nucleolus:
- Produces ribosomes Both

Nucleoplasm:
- Gelatinous (Jelly like substance)
- Contains DNA (Chromatin)

Vacuoles - Storage of macromolecules

- Stores harmful substances
- Animal cells have lots of small vacuoles and plant cells have one Both
large vacuole
- Keeps plants firm by pressing against cell wall

Vesicles - For transport of substances. Both

Rough Endoplasmic - Processes and transports proteins.

Reticulum (RER) - Studded with ribosomes. Both
- Ribosomes carry out protein synthesis.

Smooth Endoplasmic - Makes lipids and steroids

Reticulum (SER) - Carbohydrate metabolism
- Breaks down drugs and toxins (detoxification) in the liver Both
- Storage & release of calcium (for muscle movement)

Ribosomes - Builds proteins

- Found on rough endoplasmic reticulum or free-floating in cytosol Both

Cytoskeleton - Network of fibers

- Provides support and structure Both
- Allows movement in cell

Cell Wall - Surrounds cell membrane

- Strong and rigid Plant
- Provides support to cell

Cell Membrane - Separates and protects the cell from its surroundings.
- Regulates what enters/exits the cell (selectively permeable) Both
 Cytoplasm - Gelatinous (jelly-like) substance
- Carries out chemical reactions Both
- Supports organelles

Mitochondria - Powerhouse of the cell

- Site of cellular respiration. Both
- Breaks down glucose to produce ATP (energy).

Lysosomes - Contains digestive enzymes

- Digestion (e.g., unicellular organisms)
- Fighting disease (in white blood cells)
- Recycling cell components Animals and rarely
- Cell suicide plants

Golgi Apparatus - Modifies, stores and transports proteins from the RER and
substances like fats from the SER. Both

Chloroplasts - Site of photosynthesis

- Uses solar energy and carbon dioxide to produce glucose Plants

Centrioles Centrioles are paired barrel-shaped organelles located in the cytoplasm Animals
of animal cells near the nuclear envelope. Centrioles play a role in
organizing microtubules that serve as the cell's skeletal system. They help
determine the locations of the nucleus and other organelles within the
cell.
 Part Function

Arm - Connects the base to the body tube

- Helps to carry the microscope

Base - Supports/stabilized the microscope

- Powersource
- Lamp connects here

Lamp - Projects a beam of light towards the

specimen

Stage - Supports a slide

Diaphragm - Controls the amount of light entering

the stage opening

Stage Opening - Allows light from the lamp to focus on

a slide

Clips - Hold the slide in place

Objectives - Magnify the organism/slide low power

4x, medium 10x power, high 40x
power

Revolving Nosepiece - Allows user to switch between

different objective lenses

Body Tube - Directs light towards the eye piece

Eyepiece - Magnifies/focuses the image into the

eye
- Magnifies by 10x

Coarse adjustment - Only used with low power

- Focuses light on the slide

Fine adjustment - Used it low, medium, and high power

- Focuses fine detail
The Cell Theory and the Cell Cycle (Interphase
& Mitosis)
Why are Cells so Tiny?
- Your body contains 60 trillion cells
- Cells take in nutrients and dispose of waste through the cell membrane
- As cells grow larger, the volume grows faster than the membranes’ surface area
- When the cell becomes too large to absorb enough nutrients it must divide

Why do Cells Divide?

- Growth:
- To increase the number of cells in the body
- Repair:
- To replace dead, damaged or old cells
- Reproduction:
- Can make exact copies (clones)

The Cell Cycle

- Every hour, about 1 billion of your cells die and another 1 billion are made
- Body cells go through several stages in their lifetime called the Cell Cycle

The Cell Cycle has 2 parts:

1. Interphase:
-Cell repairs any damages, re-energizes, grows and prepares for division.
2. Mitosis & Cytokinesis:
-Division of the cell into 2 identical “daughter” cells.

- In humans, different types of cells have different lengths of this cycle. The average skin
cell life is between 14-28 days, while the red blood cell lives up to 120 days

Interphase
- Longest stage of the cell cycle, a cell spends 90% of its time here
- Divided into three phases
 First Gap Phase (G1):
- Cells grow in size. New proteins and organelles are made

Synthesis Phase (S):

- DNA is replicated (known as chromatin)

Second Gap Phase (G2):

- Cells prepare for division

Cell Division
1. Mitosis (division of the contents of the nucleus)
- Prophase
- Metaphase
- Anaphase
- Telophase

2. Cytokinesis (division of the cytoplasm/organelles)

- Original cell splits into two daughter cells

Chromosomes
- Hereditary information
- Contained within the nucleus
- Human cells contain 23 pairs of chromosomes
- When a cell divides, each daughter cell gets the same 23 pairs of chromosomes
- Composed of DNA and proteins
- A gene is a segment of DNA that codes for a particular trait

Prophase Metaphase Anaphase Telophase Cytokinesis

-Chromatin condenses -Spindle fibers attach -Spindle fibers -Spindle fibers -Cell membrane
to form paired to centromeres shorten disappear pinches inwards
chromosomes (sister
chromatids) -Chromosomes line -Centromere splits -Chromosomes -Cytoplasm splits
up at metaphase plate begin to untangle as in half
-Centrioles move to -Sister chromatids chromatin
each pole separate and move -Daughter cells
to opposite poles as -Nuclear membrane return to interphase
-Nucleolus disappears daughter reappears around
chromosomes DNA
-Nuclear membrane (pulled by spindle
breaks down fibres)
Purpose of the Cell Cycle
Cellular division like this is necessary for the body to continue functioning successfully. Skin
cells, and cells in the digestive tract, continually undergo cell division as they are likely to be
damaged or injured. However, nerve cells do not undergo mitosis, and this is why spinal cord
damage can be so detrimental.

Go Phase
- Cells can enter a resting phase called Go
- e.g., nerve cells in the brain stop dividing when the brain is developed and cannot reenter
the cell cycle

Cell Death
Necrosis:
- Cells may die due to external factors
- e.g., Toxins, infections, trauma

Apoptosis:
- The controlled death of old cells
- e.g., White blood cells divide to fight viral infections. When they are no longer required,
they undergo apoptosis

Cancer
- Genetic mutations can cause cells to mutate and undergo abnormal cell division
- Instead of undergoing apoptosis, these cells divide uncontrollably
- A cancer cell can continue to divide without limit, compared to a normal healthy cell
which has an upper limit of 50 - 60 divisions
- Cell division occurs so fast that cells pile up on top of one another, forming a tumor
- Reduces the effectiveness of the surrounding tissue
- Changes to these abnormal cells in the tumor can create cancer
 - May invade and destroy neighbouring cells
- May stimulate other cells to start replicating uncontrollably, thus spreading cancer and
causing different types of cancer

Normal Cells Cancer Cells

- Make exact copies of themselves through - Make exact copies of themselves through
mitosis mitosis

- Reproduce for about 50-60 cell divisions - Do not stop reproducing

- Stick together to form masses of cells as - Do not stick to other cells, behave
appropriate independently

- Self-destruct when too old or too damaged - May move to another location in the body

Cell Specialization
Why Specialization?
- A single cellular organism performs all required functions in one cell
- e.g., Amoeba
- Multicellular organisms are much more complex
- The body needs to supply food and nutrients, transport materials, remove wastes and
fight infection

Cellular Differentiation
- The process of creating specialized cells
- All cells in the body originated from the zygote undergoing mitosis
- As an embryo develops, cells change their shape, contents and function

What Causes Specialization?

1. Cytoplasm Differences:
- Asymmetric distribution of organelles & other factors in zygote
- Results in different daughter cells
2. Environmental Conditions:
- Variations in temperature and nutrients

3. Neighbouring Cells:
- Substances produced by nearby cells can diffuse to nearby cells

The three factors listed may result in the expression of different genes within a cell.

Abnormal Development
- Chemical contamination of the environment can affect cellular development

Stem Cells
- Cells that can differentiate into many different cell types
- The daughter cells have the same DNA, but different genes may be turned on or off

Types of Stem Cells

1. Embryonic Stem Cells
- Differentiates into any cell type

2. Adult Stem Cells

- Exists in some tissues but can only form specific types of cells
- E.g., bone marrow stem cells form white blood cells, red blood cells and platelets

Tissue Types
- Tissues are a collection of similar cells that perform specific functions
- Animals have 4 types of tissue:
1. Epithelial
a. Line the internal and external surfaces of the body
b. Form a barrier by connecting adjoining cell membranes
2. Muscular
a. Move the body or organ by contracting and relaxing
3. Connective
a. Strengthens, supports and protects other tissues
b. Cells are in an extracellular matrix
4. Nervous
a. Made of neurons with long projections that send and receive signals
b. Coordinates body actions
Human Organ Systems
Organ Systems
- Circulatory
- Respiratory
- Digestive

Circulatory System
Functions:
- Transports nutrients and oxygen to the body cells for cellular respiration
- Remove wastes and carbon dioxide from the cells, from cellular respiration and other
cellular processes
Components:
- Heart
- Cardiac muscle tissue causes the heart to contract as one unit
- Epithelial tissue lines the inside and outside of the heart to protect it from friction
- Blood Vessels
- Arteries:
- Carry blood away from the heart
- Veins:
- Carry blood toward the heart
- Capillaries:
- Surround each body cell
- Allows oxygen and nutrients to enter cell
- Blood
- Red blood cells:
- Transports oxygen to cells
- White blood cells:
- Recognize and destroy foreign microbes
- Platelets:
- Cell fragments involved with blood clotting
- Plasma:
- Protein-rich liquid that carries blood cells

Respiratory System
Functions:
- Provides oxygen needed by the body for cellular respiration.
- Removes carbon dioxide from the body (waste from cellular respiration)
Components:
 - Mouth and nose
- Trachea
- Air from the mouth and nose pass through the trachea
- Cartilaginous rings keep it open
- Lined with ciliated epithelium
- Cilia ‘beat’ to move mucus and foreign debris away from lungs
- Lungs
- Bronchi
- Alveoli
- Non-muscular organ filled with alveoli
- Alveoli are small air sacs surrounded by capillaries
- Diaphragm
- Dome-shaped muscle
- Attached to bottom lungs

Digestive System
Function:
- To take food into the body
- To break down food into smaller pieces
- To absorb nutrients into the body
- To excrete solid waste

Components:
- Mouth
- Breaks down food
- Chewing
- Digestive enzymes
- Saliva produced by epithelial tissue
- Esophagus
- Smooth muscles contract and relax to push food to the stomach
- Stomach
- Stores food
- Smooth muscle contracts to mix food with digestive juices
- Small intestines
- Villi and Microvilli
- Digestion and then absorption of nutrients through villi and microvilli
- Absorbed into capillaries for cellular respiration.
- Large intestines
- Water reabsorbed into body
- Solid matter excreted as feces from anus
Homeostasis
A certain range of physical and chemical conditions are required for the body to operate.
Examples include:
- Blood sugar levels
- Blood oxygen levels
- Body temperature
The tendency of an organism to maintain a steady state condition is called homeostasis.

Interactions of Systems
- Oxygen moves from air in the respiratory system to blood in the circulatory system
- Carbon dioxide moves from blood to air (in lungs)
- Nutrients move from food in the digestive system from villi and microvilli to the blood
through capillaries in the circulatory system
- Oxygen and nutrients move from the circulatory system (capillaries) into body cells for
cellular respiration
- Carbon dioxide from cellular respiration and wastes move from body cells into
circulatory system (capillaries)

Cellular Respiration:
Glucose + Oxygen → Carbon Dioxide + Water
- Respiratory system
- Brings oxygen to mitochondria, removes carbon dioxide as waste
- Digestive System
- Brings nutrients (glucose) to mitochondria
- Circulatory System
- Transportation

Plant Tissues
Meristematic Cell Tissue
- Unspecialized
- Divide and differentiate into specialized tissues

Dermal Tissue
- Forms the outermost layer of a plant
 - Epidermis can be specialized:
- Epidermal root cells can form root hairs to absorb water and minerals
- Epidermal leaf cells produce a waxy waterproof cuticle

Vascular Tissue
Xylem
- Transports water and dissolved minerals from the roots to the leaves.
Phloem
- Transports a sugar solution from the leaves to the roots.

Ground Tissue
- Located between the dermal and vascular tissue
- Perform a variety of functions:
- Photosynthesis
- Food and water storage
- Structural support