Cells

Essential Question: What are cells and how are they organized? Vocabulary: cellprokaryotes organismeukaryotes unicellularautotrophic multicellularheterotrophic stimulus

1. Cells a. the basic unit of structure and function in an organism b. composed of chemicals 1. water- most abundant chemical 2. carbohydrates- cell’s energy source 3. proteins- building materials 4. lipids- building materials 5. nucleic acid- genetic material a. the chemical instructions that direct cells activities c. a microscope is used to view cells 1. uses lenses to magnify small objects.

2. The First Cells a. 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 accumulated 3. became forerunners of the first cells b. used experiments to produce carbohydrates, proteins, lipids and nucleic acids. c. evidence from fossils 1. fossils- traces of ancient organisms preserved in rock a. oldest fossil of bacteria-like cells found in Australia b. approximately 3.5 billion years old c. believed to be Earth’s earliest life forms

3. Cell Types and Structure A. Bacterial cell 1. unicellular – single celled organism 2. the most numerous organism on Earth 3. cell carries out all functions necessary for the organism to survive. 4. come in 3 different basic shapes a. spherical- round ball like bacteria b. rod-like long, thin bacteria c. 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 parts a. cell wall- outermost structure of the cell 1. its chemical make-up determines what shape the cell will be 2. protects the cell b. cell membrane- located inside the cell wall 1. controls what material pass into and out of cell c. cytoplasm- region located inside the cell membrane 1. made of a gel-like substance d. ribosomes- located in the cytoplasm 1. chemical factories that produce proteins e. genetic material- also located in the cytoplasm 1. looks like tangled up string 2. contains the instructions for all the cell’s functions and operations f. flagellum- extends out through the cell membrane and cell wall 1. long, whip-like structures 2. helps cell move using a back and forth motion 3. 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 Cells 1. have the same type of structure as a bacterial cell a. cell wall- made mostly of cellulose 1. cellulose is a chemical that makes the walls of a plant cell rigid 2. shape of a plant cell is like a box b. contain chloroplasts 1. look similar to green jelly beans 2. structure in which food is made c. also have vacuoles 1. large sac-like storage area 2. stores many substances including water, food and wastes 3. expands like a balloon when water enters it and shrinks when water leaves d. has a nucleus 1. dense area that contains the nucleic acids, which instructs and directs the cells activities

C. Animal Cells 1. similar to bacterial and plant cells in structure 2. lacks a cell wall a. 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 collagen a. animals are the only organism that use this particular protein

D. Organisms 1. any living thing 2. can be unicellular- or single celled a. one cell carries out all the functions needed for the organism to survive b. (e.g.) bacterial cell 3. can be multicellular- composed of many cells a. cells are specialized to do certain tasks b. (e.g.) plants and animals 4. specialized tasks of organisms are divided into four categories a. E nergy Use 1. cells digest food 2. move chemicals 3. repair damage b. G rowth and Development 1. growth- the process of becoming larger 2. development- process of change to produce a more complex organism 3. use energy to create new cells

c. R esponse to Surroundings 1. all organisms react to changes in their environment a. stimulus (stimuli) - change in the environment that causes an organism to react 1. temperature 2. light 3. sound 4. other factors 2. an organism reacts to stimulus with a response a. response- an action or change in behavior 1. (e.g.) someone jumps at you (stimulus), you jump and/ or scream (response)

d. Reproduction 1. organisms have the ability to produce offspring similar to parents a. asexual reproduction 1. reproductive process that involves one parent and produce offspring that are identical to the parent 2. binary fission- one cell divides to form two identical cells 3. mitosis- cell divides at the nucleus 4. bacteria produce other bacteria exactly like themselves b. sexual reproduction 1. involves two parents who combine their genetic material to create a new organism 2. animals produce babies 3. plants produce new seeds for creating new plants

E. The Six Kingdoms 1. organisms are classified into kingdoms based on… a. their type of cells b. 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- Archaebacteria a. means “ancient bacteria” b. unicellular- single celled c. live only in places without oxygen 1. ocean floor 2. hot springs d. are prokaryotes- organisms that lack a nucleus 1. nucleic acid is scattered throughout the cell

Kingdom #2- Eubacteria a. unicellular- single celled b. also lack a nucleus c. chemical make-up is different from archaebacteria d. most eubacteria are helpful 1. produce vitamins 2. produce foods like yogurt 3. recycle essential chemicals like nitrogen Kingdom #3- Protists a. some organisms are autotrophic 1. produce their own food b. others are heterotrophic 2. cannot produce food themselves c. most protists are unicellular d. some are multi-cellular e. all protists are eukaryotes 1. organisms with cells that contain nuclei

Kingdom #4- Fungi a. multicellular b. eukaryotes- cells contain nuclei 1. mushrooms 2. molds 3. mildew 4. yeast- unicellular c. found almost anywhere on land d. only a few are found in fresh water e. all fungi are heterotrophs 1. cannot produce their own food 2. obtain food from decaying plants in soil Kingdom #5- Plants a. all multicellular b. all eukaryotes- cells containing nuclei c. all plants are autotrophs 1. make their own food d. 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 multicellular b. all are eukaryotes- organisms with cells that contain nuclei c. all animals are heterotrophs 1. they cannot make their own food d. have many different adaptations 1. allows them to locate food 2. capture food, if necessary 3. eat food 4. digest food e. also live in very diverse environments on Earth