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BIOLOGY 1021
UNIT 1: MULTICELLULAR
STRUCTURE
CHAPTER 15 P. 307-311
AND
CHAPTER 16 P. 328-331
Be sure to know flow chart – an
understanding from atoms to multicellular
organisms.
Importance of carbon, hydrogen, proteins, carbohydrates,
phospholipids, various cellular organelles and their
functions
TWO TYPES OF CELLS (Prokaryotic and Eukaryotic)
Cell
functions:
metabolism
and transport
etc.
REVIEW
REVIEW OF UNICELLULAR ORGANISMS
• Unicellular – 1 cell is the entire organism, microscopic but a highly efficient metabolic machine.
• All life processes must take place within or by that one cell…..
• Reproduction
• Movement
• Diffusion
• Osmosis
• Active transport
• Respiration
• DNA replication
• Protein synthesis enzyme reactions
• Homeostasis…etc..
Unicellular organisms include Bacteria (prokaryotic) and some Protists (Eukaryotic)
• Main disadvantage of being unicellular is the fact if the cell is destroyed then
the organism is also destroyed!
• Protection and Reproduction is VERY important!
1. Produce high number of offspring for very large populations.
2. Have capsule (or pellicles), cell wall and membranes for protection.
3. Sexual reproduction to increase genetic variety (need more energy
so this type of reproduction is less frequent because they prefer to
reserve energy for other metabolic functions needed to survive.
4. Reproduce asexually until it is absolutely necessary to revert to
sexual reproduction.
https://study.com/academy/lesson/kingdom-protista-
definition-characteristics-examples.html
PROTISTS: TYPES OF UNICELLULAR ORGANISMS P. 308
1. Protozoans: protists that display
characteristics similar to animals.
Live in aquatic environments and
some parasitic. They are motile
(use flagella, pseudopods),
eukaryotic and heterotrophic. Ex.
Protists (Giardia – causes Beaver
Fever) (Plasmodium – causes
Malaria)
2. Slime molds – protists that appear like fungus but are not related. Unicellular in structure (have many
nuclei), able to form colonies that make them quite large in size and fungus-like, they feed on dead
plant material.
2 types – slime molds and plasmodial slime molds
TYPES OF UNICELLULAR ORGANISMS P. 309
TYPES OF UNICELLULAR ORGANISMS P. 310
3. Unicellular algae – similar to plants because they photosynthesize – phytoplankton –
they support marine food chains and webs.
Volvox – colonial green algaePHYTOPLANKTON
Dinoflagellates bloom cause RED TIDES
TYPES OF UNICELLULAR ORGANISMS P. 310-311
4. Seaweed – actually multicellular – but each cell is identical and performs its own life
processes. (later in notes) – classified in 3 different groups (Green, red and brown
algae)
UNIT 1: MULTICELLULAR STRUCTURE
• Multicellular Organisms
• To be multicellular means the organism is composed to more than one cell.
• As a result – cells are much larger and can be seen with the naked eye (still
microscopic but millions and billions of cells together eventfully produces a
structure that can be seen.)
• Multicellular organisms can be simply multicellular or multicellular with a
division of labour for life processes!
Simply Multicellular
• Some protists and fungi
• They are composed of many cells and are
thus visible in terms of size but each cell making
up the organism is behaving on its own
independent of each other.
• Like unicellular organisms, each cell is preforming all
characteristic of life, if one of the billions of cells making
up the organism is destroyed, it will occur unnoticed
and the organism continues to function unchanging.
• The numbers or quantity of cells also offers protection,
whereas in a unicellular organism structure is required
for protection.
• Disadvantage – requires excessive energy
2 types of multicellular organisms – Simple –
no division of labour
1. Multicellular protists
2. Multicellular fungi
Seaweed – multicellular – but no division of labour. Every cell
making up the seaweed will perform all the same functions
regardless of their location on the seaweed body.
1. MULTICELLULAR SEAWEED
SEAWEED
• Seaweed the grow on rocky shores are subject to
coastal action – harsh environment – but need to
live here because they need access to sunlight to
photosynthesize.
• Every cell photosynthesizes, are well protected,
perform all their own life processes therefore no
need to an elaborate transport system. Because
they are simply multicellular, they no not have any
form of skeletal or support system which explains
why, out of water, they have no shape. They simply
rely on water for support.
• Seaweed look like plants and are structurally like plants
BUT………………
• They have a holdfast that looks like a root actually holds it to
the rock
• They have a stipe which looks like a stem
• They have a blade which looks like a leaf
• In seaweeds there are no tissues, organs or organ systems, all cells
are identical. Cells of the seaweeds holdfast, stipe and blade are all
similar in appearance and perform all the same functions – every
cell photosynthesize.
• Roots, stems and leaves of a plant are organs composed of very
different tissues with different functions.
• The leaves of a plant are designed for photosynthesis
• The root of the plant are underground and is designed for
anchorage and uptake of water and nutrients – different
function – different cells so no chloroplasts
• Kingdom Fungi – is made up of multicellular eukaryotic cells that also does not form tissues, organs or
systems.
• Cells are not like other eukaryotic cells – but appear as long threads – so long that one nuclei cannot
control the entire length – therefore several nuclei are present. These cells are called hyphae.
• Fungi are composed of numerous hyphae that can make the fungi large in size (ex. Mushroom)
• All cells or hyphae are absorptive heterotrophs with the ability to produce substances to dissolve
nutrients that can then be absorbed into the cell. All cells or hyphae contain cell walls comprised of
chitin for support – as they do not have a support or skeletal system.
1I. MULTICELLULAR FUNGI P. 328
• All the hyphae in a mushroom are the same
above ground in the cap or in the stalk that is
below ground. (no division of labour)
• Fungi are very important decomposers. They help recycle nutrients.
• Beneficial.
• Eat mushrooms and truffles
• Culture fungi to produce antibiotics and other drugs - Penicillin
• Culture to make cheese and ferment alcohol
• Make bread rise
They can also be parasitic
Vaginal yeast infections, athletes foot, jock itch
P. 330
2. Multicellular with division of labour
• An organism of many cells that conserves energy, by division
of labour for life processes.
• The division of labour conserves energy via brining each
organelle together as a team and gives each a certain function.
• This creates a much more efficient organism.
• Cells Tissues Organs Organ systems
• To be multicellular with division of labour, the organism must
have tissues, organs and organ systems rather than just simply
composed of many cells
• The organisms as a result will be much larger, more complex and
highly efficient!
• Although losing one cell may not be as detrimental in term of the
organism as a whole, all components of the system must work
together since they are concerned only with their own function.
• Therefore, losing a tissue, organ and especially an organ system
WILL be detrimental to the organism as a whole, since then the
entire function will also be lost.
Tissues – a group of cells of similar shape and size that perform one specific
function. Ex. Muscle tissue – many cells working together to perform the
function of movement or contraction OR Nervous tissue – many cells working
together to perform their function of receiving and transmitting impulses.
Organs – a group of tissues working together for a specific function. Ex.
Stomach is an organ composed of several tissue types such as epithelial tissue,
muscle tissue ans connective tissue, all working for breakdown of materials.
Organ system – A group of organs working together for a specific function. Ex.
Digestive system is composed of various organs such as the stomach, intestine,
colon whose function is digestion. The cardiovascular system is composed of
vital organs such as the heart, veins, arteries that work together for transport.
LAB # 1