Download 1 Cells Cells -Cells are the building blocks of living things

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Cells
Cells
-Cells are the building blocks of living things
-The function of the cell is to make proteins
-the cell is a big protein factory
-There are 5 types of living things:
1. bacteria- unicellular
2. protists
3. fungi
multicellular
4. animals
5. plants
The Electron Microscope
-most cells are too small to see with the unaided eye
-electron microscopes can magnify very tiny cell parts and even some large molecules more than a
million times
-drawbacks:
- you can’t observe living things with it because the steps to prepare the sample kill it
-preparation can also alter cell structures
-scanning tunneling microscopes can be more powerful than electron microscopes and don’t kill
samples, but can only reveal surface features
Cell theory
1. cells are the basic units of structure and function of living things
2. all cells come from preexisting cells
3. all living things are composed of cells
Robert Hooke
*discovered and named cells
-examined cork through a microscope
-saw rows of box-like structures he could see through
- reminded him of rooms that monks lived in, so he called them cells
Robert Brown
*discovered the nucleus
M.J. Schleiden:
*discovered that all plants are made of cells
- plant cells that contain nuclei and cell fluid
- he was a botanist
Theodor Schwann:
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*discovered all animals are made of cells
-he was a zoologist
-used a microscope to look at animals
Anton van Leeuwenhoek
*discovered microorganisms in ponds water, moving around
Rudolf Virchow
*all cells come from cells
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Prokaryotes and Eukaryotes
Prokaryotes
Eukaryotes
“first cells”
*bacteria
-lack a membrane-bound nucleus
-lack intracellular membrane-bound organelles
-singular circular chromosome (DNA) or loop of
chromosomes
-simple flagella (only some)
-small ribosomes
-cell division: asexual – binary fusion
-no known cytoskeleton
-no cellulose in cell walls
*peptidoglycan = protein + glucose –very sticky
-size: very, very small
“true cells”
*protists, plants, fungi, animals
-have a membrane-bound nucleus
-have intracellular membrane-bound organelles
-multiple linear chromosomes (DNA) – they
often come in pairs
-complex flagella (only some)
-large ribosomes
-cell division: mitosis
-have a known cytoskeleton
-have cellulose in cell walls
*only plants
-size: very, very large
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Cell Structures
Prokaryotes
-unicellular organisms
-can exist in clusters, chains, and films and as isolated cells
- grow and reproduce
-nucleoid: the region where the chromosome is attached to the plasma membrane
-bacteria usually contain plasmids: one or more smaller circular DNA molecules
- contain a few genes that help bacteria survive under specific conditions
-the part of the plasma membrane, that chromosomes are attached to, can contain enzymes
-help make a copy of the chromosome before the cell divides in two
-small enzymes in the cytoplasm produce small amounts of ATP
-bacteria have 3 shapes:
-rod,
-sphere
-corkscrew
-most bacteria are autotrophs and are important producers in lakes and oceans
-bacteria are helpful: used as antibiotics and are used in foods like cheese
-cell wall
-provides structure and support for the cell
-made of stiff fibers and peptidoglycan, a sticky solution of glucose and proteins
-cell membrane
-regulates what materials enter or leave the cell
- it’s semipermeable
-composed of a phospholipid bilayer with proteins
-cytoplasm/cytosol
-the site where all chemical reactions in the cell occur
-cytoplasm = cytosol (cytosol: liquids, mostly water, and salt)
-ribosomes
-makes proteins
-links together amino acids to polypeptide chains
-made of RNA
-made of 2 parts: the small and the big part (we don’t need to know the names)
-can either be bound (attached to ER) or free (floating in cytosol)
-flagella/cilia:
-enable the cell to move
- made of protein: microtubules
-rotate like propellers or oars
-flagella
long and limited: usually 1-3
-cilia:
short and many: usually hundreds of them
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-sense substances in environment  swim towards food and away from harmful things like acid
-ex: cilia in lungs—help filter out mucus and foreign particles like dust  you sneeze
cilia in ears—sense sound waves  loud noises damage cilia: sound waves break them off
-chromosomes
-carries genetic information about characteristics of the organism
-it’s a loop:
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Eukaryotes
-mostly all are multicellular organisms
-have membrane-bound organelles
organelle: any part that has its own structure and function
- each organelle has a semipermeable membrane identical to the plasma membrane
- divides them into compartments 
- these compartments allow eukaryote cells to be more efficient by separating specific processes
and allowing division of labor
-cell (plasma) membrane
-regulates what materials enter or leave the cell
- it’s semipermeable
-composed of a phospholipid bilayer with proteins
-cell wall
-provides structure and support for the cell
-made of stiff fibers and peptidoglycan, a sticky solution of glucose and proteins
- nucleus
- contains genetic information that tells the cell how to operate
-genetic information is in chromosomes, which have DNA molecules
-chromatin
-the granular material in the nucleus
-chromosomes, or DNA, bound to protein
-chromosomes
-carries genetic information about characteristics of the organism
- consists of a single long DNA molecule wrapped around protein “spools”
-it’s a strand:
-nuclear membrane (envelope)
- controls what materials enter or leave the cell
-is a double layer of membranes—phospholipid bilayer with proteins
-surrounds the nucleus
-nucleolus
-small dense region in the nucleus
-makes RNA molecules
-the RNA that’s made here is used to make ribosomes
-cytoplasm/cytosol
-the site where all chemical reactions in the cell occur
-cytoplasm: cytosol (cytosol: liquids, mostly water, and salt) + organelles
-ribosomes
-makes proteins
-links together amino acids to polypeptide chains
-made of RNA
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-made of 2 parts: the small and the big part (we don’t need to know the names)
-can either be bound (attached to ER) or free (floating in cytosol)
- cytoskeleton
-provides structure and support for animal cells
-helps cells maintain their shapes
-composed of protein:
-microtubules: large protein structures that maintain cell shape, serve as “tracks” for
organelles, and form centrioles in cell division
-microfilaments: small protein structures that support the cell and move organelles in the cell
-holds organelles in place or move them around
-ribosomes
-makes proteins
-links together amino acids in polypeptide chains
-made of RNA
-made of 2 parts: the small and the big part (we don’t need to know the names)
- smooth endoplasmic reticulum (ER)
-makes molecules used by the cell, especially lipids
-makes materials for inside the cell
-no attached ribosomes
- rough endoplasmic reticulum (ER)
-makes proteins for the membrane
-modifies proteins: folds amino acids into polypeptide chains
-forms tubes and channels: amino acids made in ribosomes get folded and glucose chain is added as
receptors/cell markers
-carries proteins and other out of cells through these channels
-makes materials for outside the cells
-has attached ribosomes
- golgi apparatus
-modifies, sorts, and packages molecules for use
-materials come into and leave through vesicles
-transport vesicles pinch off and carry molecules (these vesicles have a membrane)  fuses with
membrane of golgi apparatus  it packages materials in vesicles  vesicles pinch off the golgi
membranes
-proteins made by ribosomes are modified here  proteins go from primary to secondary or tertiary
levels
-enzymes attach carbohydrates and lipids to protein
ex: glucose attached to proteins  they become part of external structure  helps plants
and fungi build cell walls and animal cells build protein fibers that strengthen organs like your
skin
- vesicles
-transports materials within, into and out of the cell
-small temporary structures (in contrast to vacuoles)
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-can fuse with the plasma membrane, releasing materials from the cell
-can fuse with membranes of other organelles, transporting materials
- lyosomes
-contain digestive enzymes that are used to break down food, cell parts, and old cells
-sometimes called suicide sacs
-if lyosomes burst, it kills the entire cell
-the cells commit “suicide”  reshapes organisms
-ex: tadpoles becoming frogs, humans losing baby flat
- vacuoles
-large storage structures primarily for water, salts, and sugars in plants
-large, permanent structures
-only in plants
-enlarge as cells mature
-90% of the matured cell is a vacuole
-flagella/cilia:
-enable the cell to move
- made of protein: microtubules
-rotate like propellers or oars
-flagella
long and limited: usually 1-3
-cilia:
short and many: usually hundreds of them
-sense substances in environment  swim towards food and away from harmful things like acid
-ex: cilia in lungs—help filter out mucus and foreign particles like dust  you sneeze
cilia in ears—sense sound waves  loud noises damage cilia: sound waves break them off
- chloroplasts
-makes glucose
-takes carbon dioxide and water and turns it into glucose
-CO2 + H2O  C6H12O6 + O2 *photosynthesis- takes energy from the sun*
-has 2 envelope membranes – one oval and one that looks like stacks
-benefit: more surface area
-is green because of the chlorophyll
-in autotrophs only: heterotrophs can get glucose from digestion, but autotrophs make their own
- mitochondria
-produces ATP for the cell
-has 2 envelope membranes: the one on the inside is convoluted
-benefit: more surface area
-rod-shaped structures
-autotrophs- takes glucose made in chloroplasts
-heterotrophs- glucose goes in the membrane through transport proteins
-centrioles
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-help move chromosomes during cell division
-bundles of microtubules
-usually found near the nucleus
-found in animals  can’t see them in plant cells
-cilia are short flagella
cells that have cilia are often covered with hundreds of them
can move cells along with an oar-like motion
can move materials along a cell or tissue
ex: cilia in lungs help filter out mucus and foreign particles like dust
The Cell as a Factory
-cytoskeleton = steel beams and columns
-nucleus = main office
-ribosome = factory machines
-golgi apparatus = customization shop
-chloroplasts = solar power plants
-mitochondria = oil-burning furnaces
Plant cells vs. Animal cell
-some cell structures are specific to either plant or animal cells
-only plants have chloroplasts and mitochondria:
-benefit: they have 2 sites of making energy
-only plants have a cell wall
-benefit: extra support for the cell
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Unicellular and Colonial Cells
- prokaryotes can exist in clusters, chains, and films and as isolated cells
-each cell is an individual organism and can break away at some point
-some unicellular microorganisms live in groups call colonies
-members of a colony are usually related
-each cell is still a separate organism
-ex: some bacteria that attach to solid objects form colonies called biofilms
-a biofilm may contain several unrelated types of bacteria that require similar environments
-in some colonies individual cells take on specialized roles
-ex: volvox is one of many types of colonial algae
-it’s a colony shaped like a hollow ball
-inside the colony may be other developing colonies
-each colony has several hundred to tens of thousands of cells
-has larger cells at the front and delicate strands of cytoplasm connecting the cells
-moves in a coordinated way—spins on its front-to-rear axis  each cell’s flagella move in the
same pattern
-if a volvox cell is punctured, the cell dies, but the rest of the colony lives
Multicellular Organisms- division of labor
-plants and animals have created more surface area with structures like lungs, blood vessels, and leaves
-cells have different functions that they carry out
ex: gland cells, nerve cells, muscle cells, epidermal cells
-epidermis: an organism’s outer covering
5 levels of organization: specialization
-no matter how specialized the structures in an organism become, they are still made from cells
-cell develop to perform specific functions
-specialized cells perform specific functions with the organism
-the human body contains scores of different cell types
-some cell are specialized to react to the environment
-organisms: groups of organ systems that function together
human, dog, fish, lizard, bird
-organ systems: groups of organs that function together
digestive, respiratory, circulatory(heart, blood, blood vessels), nervous, cardiovascular
-organs: groups of tissues that function together
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heart (cardiac muscle tissue), kidney, brain, lung, skin
-tissues: groups of cells that function together
-muscle tissue (cardiac, skeletal, and smooth muscle cells), blood (red and white blood cells), skin
(epidermis and muscle cells)
-tissues in our body: cardiac tissue, fatty tissue, and connective tissue
-tissues types:
1. connective- bone, cartilage, blood, lymph
2. muscle
3. epithelium- is the internal or external covering that provides protection, like your skin or
the internal covering of your cheek’s
4. nerve
-cells : the basic units of life
-red blood cells and white blood cells, epidermis, secretory, cardiac, skeletal, and smooth muscle
Systems
-in multicellular organisms, cells can’t obtain nutrients or pass wastes directly with their environment
-so: specialized systems, like a circulatory system, are used for the transport of materials
-plants also have transport systems— exchange gases with stomatal openings; nutrients are absorbed
through roots and go to leaves
-so: carries food produced in leaves to other parts of the plant
-3 things systems are needed for:
1. a division of labor (aka levels of organization)
2. many individual cells can’t work together without regulation and coordination
3. cells aren’t in direct contact with the outside environment
-organ systems do many things—they aren’t just specialized for one function
ex: circulatory system transports materials and protects the body from infection
-cells are the lowest level of organization that can be considered living
Levels of Structure in the Biosphere
biosphere – the part of earth that contains life
ecosystem – chesapeake bay
community – all organisms in chesapeake bay
population – all striped bass in chesapeake bay
organism – striped bass
organ system – circulatory system
organ – heart
tissue – muscle
cell – blood cell
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organelle – mitochondrion
macromolecule – hemoglobin
molecule – water
atom – hydrogen
subatomic particle – proton
elementary particle – quark
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