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STANDARD 2
Organization & Development of
Living Systems
Unit 2 – Cell Structure & Function
Objectives
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B2.4h: Describe the structures of viruses and bacteria.
B2.5g: Compare and contrast plant and animal cells.
B2.5i: Relate cell parts/organelles to their function.
B1.1E. Give evidence to support conclusions
B1.2E Be aware of careers in science
B1.2h Distinguish between theories, hypotheses and
observations
• B1.2i Explain progressions of ideas
What is Biology?
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Bio- = life
-ology = study of
Biology= study of life
3 types of items
• Living
• Non living
• Dead
Carbon: The Element of Life (4:00)
Characteristics of Life
6 Generally accepted characteristics common to all
living things:
1. Cells – have at least one cell
1. Have coded “information molecules” with instructions
for organization and activities.
2. Metabolism- Obtain and use energy from
environment and give off byproducts
1. Heterotrophs = get energy from other organisms.
2. Autotrophs = synthesize their energy through
photosynthesis / make their own food
Characteristics of Life …
• 3. Growth and Development
• 4. Homeostasis – Ability to regulate internal
environment - balance
• 5. Reproduce - Make more of its kind; pass on genetic
material
• 6. Require Water
• If something is not alive it is either non- living or dead.
– What is the difference?
Characteristics of Life (5:58)
VIRUSES
Where Do Viruses Fit?
• Viruses are not classified as cells and therefore are neither unicellular nor
multicellular organisms.
• Most people do not even classify viruses as "living" because they lack a
metabolic system and are dependent on the host cells that they infect to
reproduce.
• Viruses have genomes that consist of either DNA or RNA, and there are
examples of viruses that are either double-stranded or single-stranded.
Importantly, their genomes code not only for the proteins needed to package
its genetic material but for those proteins needed by the virus to reproduce
during its infective cycle.
How Viruses Work (02:25)
The Littlest Assassins: What Are Viruses? (03:35)
Viruses
Are viruses alive?
- Viruses lack cellular structure but have genetic
material to invade living cells.
Bacteria Cell Structure
Animal Cell Structure
CELLS
INTRODUCTION TO CELLS:
• Discovered by Robert Hooke, an English naturalist.
– He was looking at cork.
– The cork was dead, but the cell walls remained.
– Hooke coined the term "cells": the boxlike cells of cork
reminded him of the cells of a monastery.
– The term cell came from the Latin word cella which means
"storeroom" or "small container".
INTORDUCTION TO CELLS:
• Anton Van Leeuwenhoek, a Dutch businessman and a
contemporary of Hooke, used his own (single lens)
monocular microscopes & discovered living cells 10 years
later in pond water.
– Leeuwenhoek succeeded in making some of the most
important discoveries in the history of biology. It was he
who discovered bacteria, free-living and parasitic
microscopic protists, sperm cells, blood cells, microscopic
nematodes and rotifers, and much more.
BACTERIA
Organisms Found in Pond Water:
Bacteria and Algae (03:37)
PROTISTS
SPERM CELLS
CELL THEORY
The modern tenets of the Cell Theory include:
* 1. All known living things are made up of cells.
* 2. The cell is structural & functional unit of all living things.
* 3. All cells come from pre-existing cells by division.
(Spontaneous Generation does not occur).
4. Cells contains hereditary information which is passed from
cell to cell during cell division.
5. All cells are basically the same in chemical composition.
6. All energy flow (metabolism & biochemistry) of life occurs
within cells.
The Living Cell (20:00)
The concept was
formally articulated in
1839 by Schleiden &
Schwann.
The cell theory also
provides us with an
operational definition
of "life“.
WHAT IS A CELL?
• Cells are the structural and functional units of all living
organisms. Some organisms, such as bacteria, are unicellular,
consisting of a single cell. Other organisms, such as humans,
are multicellular, or have many cells—an estimated
100,000,000,000,000 cells! Each cell is an amazing world unto
itself: it can take in nutrients, convert these nutrients into
energy, carry out specialized functions, and reproduce as
necessary. Even more amazing is that each cell stores its own
set of instructions for carrying out each of these activities.
Cells – The Basic Units of Life (1:49)
2 TYPES OF CELLS:
• 1. Prokaryote
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Single celled (unicellular organisms)
Lack membrane bound organelles
Single stranded DNA – no nucleus
Most of the functions of organelles, such as mitochondria,
chloroplasts, and the Golgi apparatus, are taken over by the
prokaryotic plasma membrane. Example- only Bacteria
• 2. Eukaryote
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More complex
Have membrane bound organelles / nucleus
Multiple strands of DNA in the nucleus
include fungi, animals, plants as well as some unicellular organisms
Eukaryotic cells are about 10 times the size of a prokaryote
Example - Plants and animals
2 TYPES OF CELLS:
Two Types of Cells: Prokaryotic and Eukaryotic (00:40)
This figure illustrates a typical human cell (eukaryote) and a typical bacterium
(prokaryote). The drawing on the left highlights the internal structures of eukaryotic cells,
including the nucleus (light blue), the nucleolus (intermediate blue), mitochondria
(orange), and ribosomes (dark blue). The drawing on the right demonstrates how bacterial
DNA is housed in a structure called the nucleoid (very light blue), as well as other
structures normally found in a prokaryotic cell, including the cell membrane (black), the
cell wall (intermediate blue), the capsule (orange), ribosomes (dark blue), and a flagellum
(also black).
PROKARYOTES
• Cells that lack a membrane-bound nucleus are called
prokaryotes (from the Greek meaning before nuclei).
• Cells in the monera kingdom such as bacteria and
cyanobacteria (also known as blue-green algae) are
prokaryotes.
• Prokaryotic cells differ significantly from eukaryotic cells. They
don't have a membrane-bound nucleus and instead of having
chromosomal DNA, their genetic information is in a circular loop
called a plasmid.
Prokaryotic Cells (02:28)
PROKARYOTES…
• Bacterial cells are very small, roughly the size of an animal
mitochondrion.
• Prokaryotic cells feature three major shapes: rod shaped,
spherical, and spiral.
• Instead of going through elaborate replication processes like
eukaryotes, bacterial cells divide by binary fission.
• Bacteria perform many important functions on earth. They
serve as decomposers, agents of fermentation, and play an
important role in our own digestive system.
• Also, bacteria are involved in many nutrient cycles such as
the nitrogen cycle, which restores nitrate into the soil for
plants.
EUKARYOTES
• Eukaryotic cells (from the Greek meaning truly nuclear) comprise all of
the life kingdoms except monera. They can be easily distinguished
through a membrane-bound nucleus.
• Eukaryotic cells also contain many internal membrane-bound structures
called organelles. These organelles such as the mitochondrion or
chloroplast serve to perform metabolic functions and energy conversion.
• The cell is the basic structural unit of life, and the smallest unit of
biological entities that are considered "alive."
EUKARYOTES…
• Each cell represents a miniature organism, in a sense, in that cells perform
necessary functions such as respiration, consumption of nutrients, and
expulsion of metabolic wastes to continue their existences.
• As such, cells have developed specialized structures called organelles to
aid them in these specific functions such as respiration and photosynthesis.
• Eukaryotic cells are much larger and more advanced than prokaryotic cells.
• Most importantly, eukaryotes reproduce sexually.
• Genetic material is mixed between two parents, and while the offspring
resembles the parents in major features, minor genetic variations can yield
subtle differences. The new characteristics sometimes help eukaryotic
organisms to adapt to new environments.
Eukaryotic Cells (03:22)
Plant Cell
Animal Cell
EUKARYOTE ORGANELLES
• ORGANELLES of eukaryotic cells (each has their own function):
• The human body contains many different organs, such as the heart, lung,
and kidney, with each organ performing 0a different function. Cells also
have a set of "little organs", called organelles, that are adapted and/or
specialized for carrying out one or more vital functions. Organelles are
found only in eukaryotes and are always surrounded by a protective
membrane.
Plasma Membrane
Cell Walls and Cell Membranes (01:53)
A lipid/protein/carbohydrate complex, providing a barrier
and containing transport and signaling systems.
(controls movement in/out of cell to maintain homeostasis)
Eukaryotic Cells: Nucleus (00:42)
Nucleus
Double membrane surrounding the chromosomes and
the nucleolus. Pores allow specific communication with
the cytoplasm. The nucleolus is a site for synthesis of
RNA making up the ribosome.
(brain of cell)
EUKARYOTE ORGANELLES
• Cytoplasm = Inside the cell there is a large
fluid-filled space, it is the "soup" within
which all of the cell's organelles reside. The
nucleus often flows with the cytoplasm
changing its shape as it moves. The
cytoplasm also contains many salts and is
an excellent conductor of electricity,
creating the perfect environment for the
mechanics of the cell. The function of the
cytoplasm, and the organelles which reside
in it, are critical for a cell's survival. (fills all
empty space & allows movement & reactions)
• Nuclear Envelope = The nucleus is
spheroid in shape and separated from the
cytoplasm by a membrane called the
nuclear envelope. The nuclear envelope
isolates and protects a cell's DNA from
various molecules that could accidentally
damage its structure or interfere with its
processing. (protects nucleus / controls in/out))
EUKARYOTE ORGANELLES
Mitochondria
Organelles: Mitochondria (00:38)
Surrounded by a double membrane with a series of folds
called cristae. Functions in energy production through
metabolism. Contains its own DNA, and is believed to
have originated as a captured bacterium. Mitochondria
play a critical role in generating energy in the eukaryotic
cell, and this process involves a number of complex
pathways. Once inside the cell, glucose is broken down
to make adenosine triphosphate (ATP), a form of energy.
(powerhouse of cell)
Chloroplasts and Photosynthesis (00:50)
Chloroplasts (plastids)
Are similar to mitochondria but are found only in plants.
Surrounded by a double membrane, containing stacked
thylacoid membranes. Chloroplasts convert light energy
from the sun into ATP through a process called
photosynthesis. Contains DNA, and like mitochondria is
believed to have originated as a captured bacterium.
(collect sunlight for photosynthesis)
EUKARYOTE ORGANELLES
Rough endoplasmic reticulum (RER)
A network of interconnected membranes forming channels
within the cell. Covered with ribosomes (causing the "rough"
appearance) which are in the process of synthesizing proteins
for secretion or localization in membranes. (transport network)
Ribosomes
Making Proteins (01:54)
Protein and RNA complex responsible for protein synthesis. The
process of converting an mRNA's genetic code into the exact
sequence of amino acids that make up a protein is called
translation. Protein synthesis is extremely important to all cells,
and therefore a large number of ribosomes—sometimes
hundreds or even thousands—can be found throughout a cell.
Ribosomes float freely in the cytoplasm or sometimes bind to
another organelle called the endoplasmic reticulum.
(protein factories)
Smooth endoplasmic reticulum (SER) Endoplasmic Reticulum (00:43)
A network of interconnected membranes forming channels
within the cell. A site for synthesis and metabolism of lipids.
Also contains enzymes for detoxifying chemicals including
drugs and pesticides. (transport network)
EUKAYOTE ORGANELLES
Golgi apparatus
A series of stacked membranes. Vesicles (small
membrane surrounded bags) carry materials from the
RER to the Golgi apparatus. Vesicles move between the
stacks while the proteins are "processed" to a mature
form. Vesicles then carry newly formed membrane and
secreted proteins to their final destinations including
secretion or membrane localization.
(packages and distribution)
Lysosomes (00:39)
Often referred to as the garbage disposal system of a cell.
One function of a lysosome is to digest foreign bacteria that
invade a cell. Other functions include helping to recycle
receptor proteins and other membrane components and
degrading worn out organelles such as mitochondria.
Lysosomes can even help repair damage to the plasma
membrane by serving as a membrane patch, sealing the
wound. It is a membrane bound organelle.
(recycling centers)
Lysosymes
EUKARYOTE
ORGANELLES
Vacuoles
Membrane surrounded "bags" that contain water and
storage materials in plants.
(store water and food in plants)
Hyperlinked to
interactive cell
website
Peroxisomes
Often referred to as the garbage disposal system of a
cell. Peroxisomes function to rid the body of toxic
substances, such as hydrogen peroxide, or other
metabolites and contain enzymes concerned with oxygen
utilization. High numbers of peroxisomes can be found
in the liver, where toxic byproducts are known to
accumulate.
(remove toxics from cell)
Cell wall
Plants have a rigid cell wall in addition to their cell
membranes.
(protects and gives shape)
2 TYPES OF EUKARYOTIC CELLS:
• 1. ANIMAL
• 2. PLANT – organelles unique to plant cells:
• Cell Wall – protects and gives shape
• Chloroplasts – collect sunlight for photosynthesis
• Vacuole – large water filled storage compartment
ANIMAL CELL
PLANT CELL
Lab 1 Fresh Mount Examples:
Animal Cells (Human Cheek
cells) Stained 4x objective
Animal Cells (Human Cheek cells) Stained
40x objective
Animal Cells (Human Cheek
cells) Stained 10x objective
Lab 1 Fresh Mount Examples:
Plant Cells (Onion Epidermal
Cells) 4x objective
Plant Cells (Onion Epidermal Cells)
40x objective
Plant Cells (Onion Epidermal
Cells) 10x objective
Lab 1 Fresh Mount Examples:
Plant Cells (Elodea)
10x objective
Plant Cells (Elodea) 40x objective
Working Together
• Major systems and processes work together in animals and
plants, including relationships between organelles, cells,
tissues, organs, organ systems, and organisms.
• During the development of an animal, cells differentiate so they
can perform specific functions. Groups of cells with similar
specializations that form a common function are referred to as a
tissue. Organs are groups of several tissues that function
together. Examples of organs include kidneys, spleen, liver,
heart, lungs. Organ systems is a group of organs that work
together to perform a function. Examples of organ systems
include skeletal, muscular, nervous, digestive, respiratory,
reproductive, endocrine, circulatory, and urinary systems.
Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism
Working Together
• Hierarchical Structure of Life / Pyramid Of Life
• When you look at a pyramid, you'll notice that its broad base gradually
narrows as it extends upward. The same holds true for the organization of
life on Earth.
• Atom
– Our tour starts with the ever so tiny atom. It takes extremely powerful
microscopes to view these units of matter (anything that has mass and
takes up space). Elements such as carbon, oxygen, and hydrogen are
composed of atoms.
• Molecules
– Molecules reign supreme on the next level. Molecules are composed of
atoms and can be arranged into large molecular structures such as
chromosomes, proteins, and membranes. Some of these proteins may
be grouped together to become the organelles that make up your cells.
• Organelle
– Cells also have a set of "little organs", called organelles, that are
adapted and/or specialized for carrying out one or more vital functions.
Organelles are found only in eukaryotes and are always surrounded by a
protective membrane.
Working Together
• Cells
– The next level-- cells. Cells are the simplest form of living units. Cells
contain structures called organelles which are responsible for everything
from housing the cell's DNA, to producing energy. Processes that occur
within the body are carried out on a cellular level. For example, when you
move your leg, it is the responsibility of nerve cells to transmit these
signals from your brain to the muscle cells in your leg.
• Tissues
– Next, we have tissues. No, not the kind you use to blow your nose!
Simply put, tissues are groups of cells with both a shared structure and
function. Animal tissue can be grouped into four subunits: epithelial
tissue, connective tissue, muscle tissue, and nervous tissue.
Working Together
• Organs
– Next, we arrive at the organs: i.e., the heart, liver, brain, skin, and
stomach. Organs are composed of different types of tissue arranged
together to perform specific tasks. For example, the brain is composed of
several different types including nervous and connective tissues.
• Organ Systems
– Moving right along, we come to our next level--organ systems. Some
examples are the circulatory, digestive, nervous, skeletal, and
reproductive systems which work together to keep the body functioning
normally. For instance, nutrients obtained by the digestive system are
distributed throughout the body by the circulatory system. Likewise, the
circulatory system distributes oxygen that is taken in by the respiratory
system.
• Organism
– When all organ systems function together to form any living being, or
organism, whether plant, mammal, bird, insect, reptile, fish, crustacean,
aquatic or estuarine animal, or bacterium. These living beings have (or
can develop) the ability to act or function independently.
Basics of Biology, The: The Human Body: Organ Systems Working Together (14:39)