Cells

Essential Question: What are cells and how are they organized?

Vocabulary:

cell prokaryotesorganism eukaryotesunicellular autotrophicmulticellular heterotrophicstimulus

1. Cellsa. the basic unit of structure and function in an

organismb. composed of chemicals

1. water- most abundant chemical2. carbohydrates- cell’s energy source3. proteins- building materials4. lipids- building materials5. nucleic acid- genetic material

a. the chemical instructions that direct cells activities

c. a microscope is used to view cells1. uses lenses to magnify small objects.

2. The First Cellsa. scientists hypothesized that small chemical

units of life formed over millions of years in Earth’s waters.

1. some of these chemical units joined with each other to form large chemical

building blocks 2. chemical building blocks accumulated3. became forerunners of the first cells

b. used experiments to produce carbohydrates, proteins, lipids and nucleic acids.

c. evidence from fossils1. fossils- traces of ancient organisms

preserved in rocka. oldest fossil of bacteria-like cells found

in Australiab. approximately 3.5 billion years oldc. believed to be Earth’s earliest life forms

3. Cell Types and StructureA. Bacterial cell

1. unicellular – single celled organism2. the most numerous organism on Earth3. cell carries out all functions necessary for the

organism to survive.4. come in 3 different basic shapes

a. spherical- round ball like bacteriab. rod-like long, thin bacteriac. spiral shaped- long, thin, wavy bacteria

5. the shape of a bacterial cell helps identify the type of bacteria.

a. (e.g.)-bacteria that causes strep throat is spherical

6. Bacterial cells are made up of six different partsa. cell wall- outermost structure of the cell

1. its chemical make-up determines what shape the cell will be

2. protects the cellb. cell membrane- located inside the cell wall

1. controls what material pass into and out of cellc. cytoplasm- region located inside the cell membrane

1. made of a gel-like substanced. ribosomes- located in the cytoplasm

1. chemical factories that produce proteinse. genetic material- also located in the cytoplasm

1. looks like tangled up string2. contains the instructions for all the cell’s

functions and operationsf. flagellum- extends out through the cell membrane and

cell wall1. long, whip-like structures 2. helps cell move using a back and forth motion3. bacteria can have many flagellum or none at all

a. bacteria with no flagella use wind, water currents clothing or other objects to move from one place to

another

B. Plant Cells1. have the same type of structure as a bacterial cell

a. cell wall- made mostly of cellulose1. cellulose is a chemical that makes the

walls of a plant cell rigid2. shape of a plant cell is like a box

b. contain chloroplasts1. look similar to green jelly beans2. structure in which food is made

c. also have vacuoles1. large sac-like storage area2. stores many substances including

water, food and wastes3. expands like a balloon when water enters it

and shrinks when water leavesd. has a nucleus

1. dense area that contains the nucleic acids, which instructs and directs the cells activities

C. Animal Cells1. similar to bacterial and plant cells in structure

2. lacks a cell walla. allows a greater diversity of cell types, tissues

and organs to form

b. allows the cell to change shape

c. specialized cells that formed tissues and muscles, give animals mobility- (movement)

1. these cells did not evolve in plants

2. allowed animals to adopt many different modes of feeding,

defense, and reproduction 3. animal cells are bound together by a specific protein

called collagena. animals are the only organism that use this

particular protein

D. Organisms1. any living thing2. can be unicellular- or single celled a. one cell carries out all the functions needed for the organism to

survive b. (e.g.) bacterial cell3. can be multicellular- composed of many cellsa. cells are specialized to do certain tasksb. (e.g.) plants and animals 4. specialized tasks of organisms are divided into four categories a. Energy Use1. cells digest food2. move chemicals 3. repair damageb. Growth and Development1. growth- the process of becoming larger2. development- process of change to produce a more complex

organism 3. use energy to create new cells

c. Response to Surroundings1. all organisms react to changes in their

environmenta. stimulus (stimuli) - change in the environment that causes an organism to react

1. temperature2. light3. sound4. other factors

2. an organism reacts to stimulus with a responsea. response- an action or change in behavior

1. (e.g.) someone jumps at you (stimulus), you jump and/ or scream (response)

d. Reproduction1. organisms have the ability to produce

offspring similar to parents

a. asexual reproduction1. reproductive process that involves one parent and produce offspring that are identical to the parent2. binary fission- one cell divides to form two identical cells3. mitosis- cell divides at the nucleus 4. bacteria produce other bacteria exactly

like themselves

b. sexual reproduction1. involves two parents who combine their genetic material to create a new organism2. animals produce babies3. plants produce new seeds for creating new plants

E. The Six Kingdoms1. organisms are classified into kingdoms based on…

a. their type of cellsb. their ability to make food c. the number of cells in their body

2. the microscope led to the discovery of new organisms and differences among cells

Kingdom #1- Archaebacteriaa. means “ancient bacteria”b. unicellular- single celledc. live only in places without oxygen

1. ocean floor 2. hot springs

d. are prokaryotes- organisms that lack a nucleus1. nucleic acid is scattered throughout the

cell

Kingdom #2- Eubacteriaa. unicellular- single celledb. also lack a nucleusc. chemical make-up is different from archaebacteria d. most eubacteria are helpful1. produce vitamins2. produce foods like yogurt3. recycle essential chemicals like nitrogen

Kingdom #3- Protistsa. some organisms are autotrophic1. produce their own foodb. others are heterotrophic2. cannot produce food themselvesc. most protists are unicellulard. some are multi-cellulare. all protists are eukaryotes1. organisms with cells that contain nuclei

Kingdom #4- Fungia. multicellularb. eukaryotes- cells contain nuclei1. mushrooms2. molds3. mildew4. yeast- unicellularc. found almost anywhere on land d. only a few are found in fresh watere. all fungi are heterotrophs1. cannot produce their own food2. obtain food from decaying plants in soil

Kingdom #5- Plantsa. all multicellularb. all eukaryotes- cells containing nucleic. all plants are autotrophs1. make their own foodd. some produce flowers, others don’t e. some plants grow very tall (sequoia tree)f. some are only a few centimeters (moss)

Kingdom #6- Animals

a. all animals are multicellularb. all are eukaryotes- organisms with cells that contain nucleic. all animals are heterotrophs

1. they cannot make their own foodd. have many different adaptations

1. allows them to locate food2. capture food, if necessary3. eat food4. digest food

e. also live in very diverse environments on Earth