Unit 1: Living Systems

Section 2: Organisms: Cells to Body Systems

EVIDENCE 1: Explain using evidence how systems within our body interact to regulate overall

body functions.

Interacting Systems in Organisms

Scientists organize multicellular organisms into 5 levels, beginning with cells and moving to

increasingly complex structures.

Levels of organization

Levels of Organization for the Respiratory System

Cell – lung cells

Tissue – epithelial tissue

Organ - lung

Organ System – diaphragm, lungs, trachea, esophagus, pharynx, nose

Organism

EVIDENCE 2: How do structures in the respiratory system interact to protect the lungs? How

might a sinus infection affect the rest of the respiratory system?

EVIDENCE 3: Many organ systems interact with the circulatory system. If a person’s circulatory

system did not function properly, how might other systems, such as the respiratory and

digestive systems, be affected? How would homeostasis, or internal stability, be affected by

these system imbalances?

EVIDENCE 4: How might the digestive system and the immune system interact to help protect

the body?

Cell differentiation – the process by which cells become specialized in structure and function.

The specialization enable by differentiation is what allows different types of cells to have

different functions.

Ex. is sperm cells have a long tail called a flagellum that allows for movement.

The Cell System

Living things come in all sizes.

For example the blue whale and a tadpole. They do have cell size in common. So,

if the cells are the same size then why is there such a big difference in the size of

the tadpole and blue whale? The number of cells is what is different. The blue

whale has more.

Almost all cells are too small to see without the aid of the microscope regardless

of the size of the organism.

One of the first concepts to be developed in biology was the Cell Theory.

Cell Theory states the following

1. All organisms are made of cells

2. All existing cells are produced by other living cells. (cells come from other living

cells)

3. The cell is the basic unit of life.

Contributors to the Cell Theory

o Robert Hooke was the first to identify cells and named them.

o Anton van Leeuwenhoek made lenses for the microscope and was able to better view

cells.

o Matthias Schleiden was the first to say plants are made from cells.

o Theodor Schwann concluded that all living things are made up of cells.

o Rudolf Virchow proposed that all cells come from other cells.

Organisms can be unicellular or multicellular.

Unicellular organisms, such as amoebas, are organisms that have only one cell. They

typically live in colonies.

Multicelluar organisms, such as humans, are a collection of specialized cells that work

together. All of the cells that make up an organism arise from a single cell that goes

through successive divisions to make new cells.

Cells can be separated into two categories based on their internal structures.

1. Prokaryotic Cells – do not have a nucleus or other membrane bound organelles. The

cell’s DNA is suspended in the cytoplasm. All prokaryotes are microscopic single celled

organisms.

2. Eukaryotic Cells – have a nucleus and other membrane bound organelles. The nucleus

encloses the genetic information or DNA. Eukaryotes may be multicellular or single

celled organisms.

Eukaryotic cells have highly organized structures, including membrane-bound organelles. Plant

and animal cells share many of the same types of organelles, but both also have organelles

that are unique to their needs.

Cytoskeleton – a network of small proteins, long threads or fibers that crisscross the

entire cell and are constantly changing to meet the needs of the cell.

Cytoplasm – jellylike substance that contains dissolved molecular building blocks.

Cytosol – fluid portion of the cell and is mostly water. The water is used as a solvent for

the chemical reactions that are taking place in the cytoplasm.

Nucleus – the storehouse for most of the genetic information, or DNA, in your cells. It is

also known as the control center of the cell. This the largest and most visible organelle.

Nuclear envelope – double membrane surrounding the nucleus.

Nucleolus – a dense region of the nucleus where tiny organelles essential for making

proteins, or ribosomes, are assembled.

Endoplasmic reticulum – an interconnected network of thin folded membrane and is a

large part of the cytoplasm. Involved in protein synthesis.

o Rough endoplasmic reticulum – ER studded or covered with ribosomes

o Smooth endoplasmic reticulum – ER that does not contain ribosomes. It makes

lipids and performs specialized functions for the cell.

Ribosomes – small round structures. Can be on the surface of ER or floating freely in the

cytoplasm.

Golgi apparatus – closely layered stacks of membrane enclosed spaces that process, sort

and deliver proteins. May also be called the Golgi complex. Involved in protein

packaging and delivery.

Vesicles – small membrane bound sacs that divide some materials from the rest of the

cytoplasm and transport these materials from place to place within the cell. Short lived

and formed and recycled as needed.

Mitochondria – bean shaped and have two membranes and involved in energy

production for the cell. They have their own ribosomes and DNA which suggests that

they were once free living.

Vacuole – fluid filled sac used for the storage of materials needed by a cell. Most animal

cells contain many vacuoles where plant cells contain a central vacuole which takes to

most of the space in the cell. In a plant it’s filled with a watery substance that helps give

the plant strength and support the entire plant.

Lysosomes – membrane bound organelles that contain enzymes. They break down

damaged or worn out cell parts. Animal cells have numerous ones.

Centrioles – cylinder shaped organelles made of short microtubules arranged in a circle.

Form cilia and flagella.

Cell walls – rigid layer that gives protection, support, and shape to a cell. Only found in

plant cells.

Chloroplasts – organelles that carry out photosynthesis, making energy from the sun

and found in plant cells.

Cell membrane – also known as a plasma membrane that is flexible and separates the

inside of the cell from the outside of a cell. It protects the internal structures and

regulates movement of materials into and out of the cell.

EVIDENCE 5: Describe how the endoplasmic reticulum, mitochondria, and golgi apparatus are

structurally similar.

EVIDENCE 6: What organelles do plant cells have that animal cells do not have? What do you

think is the purpose of each of these organelles?

EVIDENCE 7: The cell walls of plants have openings, or channels. How is this structure most

likely related to the proper functioning of the plant system?

EVIDENCE 8: When a plant wilts, its leaves shrivel. How is this phenomenon related to the

function of the vacuole in the plant system?

Chloroplast vs Mitochondria

Similarities

convert energy

have its own DNA

oxygen (O2) and carbon dioxide (CO2) are involved in its processes

Differences

Chloroplast

plural: chloroplasts

usually found in plants and unicellular organisms

converts solar/light energy into chemical energy (sugar)

process is photosynthesis

has three compartments parts: thylakoids, granum and stroma.

Mitochondrion

plural: mitochondria

found in almost all cells

converts chemical energy (sugar) into another form of chemical energy (ATP), which is

simpler and could be used by the cell

process is cellular respiration

has two compartments or parts: Crista and the matrix.

EVIDENCE 9: Which would you predict would have more mitochondria – a muscle cell or a skin

cell? Explain your answer.

EVIDENCE 10: Make a claim based on evidence for how organization within the cell helps cells

function within larger systems. Use specific examples learned in earlier lecture.