Unit 3 Cells

Atoms- smallest unit of matter  Molecules/compounds  Macromolecules (lipids, etc.)  Organelles (nucleus, etc.)  Cells

The Discovery of the Cell Robert Hooke- cork Van Leeuwenhoek- pond water Play video

Cell Theory 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in all living organisms. 3. All cells come from pre-existing cells. Play video

Prokaryotes and Eukaryotes ProkaryotesEukaryotes No nucleusNucleus No membrane-bound organellesMany organelles 1-10 um in size um in size Evolved 3.5 billion years agoEvolved 1.5 billion years ago Only bacteriaAll other cells (plants, animals, complex single-celled organisms) Very basicMore complex *um = micrometers (smaller than a millimeter)

Prokaryotes DNA/genetic material rrrrrrrr rrhhhhh h Flagellum cytoplasm/ (filler) llllllllllllllllllllllllllllllllllllllll lllllllllllnnnnnnnnnnnnnnn nnnnnnnnnnnnnnnnnnn Cell wall Cell membrane

Most cells have 3 basic identifiable organelles: 1. Cell membrane: outer boundary of the cell 2. Nucleus: control center; contains the DNA 3. Cytoplasm: jelly-like filler material that bathes the organelles and transports materials within the cell from one area of the cell to another. Play video

C ell Membrane Gives cells structure and form semi-permeable Regulates what enters and leaves the cell Made up of the lipid by-layer Proteins may be embedded in the by-layer to further regulate the movement of molecules into and out of the cell Play video

Cell Wall (plants only) 1. Found only in plants, algae, and some bacteria 2. Surrounds the cell membrane 3. Porous in design; allows water, oxygen, and carbon dioxide in and out 4. 3 layers: primary layer contains pectin, secondary layer contains cellulose, and tertiary layer contains lignin (these fibrous materials are indigestible by humans).

Nucleus 1. Large dark structure in the cell 2. Center of information 3. Where DNA is found; chromosomes are the protein-based structures of genetic information. 4. Is surrounded by the nuclear envelope/membrane. 5. The nucleolus is inside the nucleus; Ribosomes are made there. 6. The DNA inside the nucleus directs the cell’s growth and development. Play video

Cytoplasm Bathes organelles Provides movement and transport within the cell Cytoplasmic Streaming moves material from one area of the cell to another.

Vacuoles Storage area for water, salts, proteins and carbohydrates. They are the most prominent in plant cells; take up to 60% of the cell. The pressure of the central vacuole makes it possible for plants support heavy structures such as leaves and flowers.

Lysosomes Small organelles filled with enzymes Digest/break down foreign material and old, worn out organelles.

Chloroplasts Round, green structures found in plant cells only; contain chlorophyll. Absorb light energy for photosynthesis Plant cells make their own chemical energy (ATP) from light energy.

Ribosomes One of the most important jobs of cells is to make proteins. Proteins are assembled on ribosomes. they produce proteins by following the instructions found in the DNA in the nucleus. Smallest organelles

Endoplasmic Reticulum (ER) Eukaryotes contain an internal membrane system called ER. Site where lipid components of the cell membrane, proteins, and other cell materials are assembled. Smooth ER (no ribosomes), stores enzymes. Rough ER (studded with ribosomes) for protein modification.

Golgi Apparatus Proteins produced in the rough ER move to the golgi apparatus. Looks like a stack of membranes Function is to modify, sort, and package proteins and other materials from the ER for storage in the cell or secretion outside the cell wall.

Mitochondrion Breaks down ingested food into chemical energy (ATP) Often called the powerhouse of the cell. Enclosed by 2 membranes: outer and inner.

Cytoskeleton The framework for the cell microtubules- 1. gives cell shape 2. forms centrioles (animal cell division) microfilaments 1. movement or support structures 2. allow for cytoplasmic streaming

Plant cells vs. Animal Cells Plant cells have the following: chloroplasts/chlorophyll for photosynthesis cell wall enlarged vacuoles geometric/blocky shape (like solar panels that fit together to eliminate wasted space) Play video

Quiz: Match the Organelle with the Number. Use the list provided. Microtubules/cytoskeleton Nucleus Nucleolus Vacuoles Golgi apparatus Mitochondria Ribosomes Membrane Cytoplasm Chromosomes Endoplasmic reticulum

Quiz: Match the Organelle with the Number. Use the list provided Chloroplasts Nucleus Vacuole Cell wall

Cell Boundaries cell membrane regulates what enters and leaves the cell. The membrane and cell wall are boundaries that separate the cell from its surroundings.

Cell Boundary

Diffusion Every cell lives in a liquid environment, even if you can’t really see it. Inside the cell is cytoplasm, which contains many substances dissolved in water (solution). In a solution, particles spread out randomly as they continuously collide with each other. As a result, particles move from an area of high concentration to an area of low concentration = diffusion. When the concentration of solute in the solution is the same throughout a system, then the solution reaches equilibrium. Diffusion does not need energy from the cell to occur.

Diffusion Play video

Osmosis Water will tend to move across the cell membrane until equilibrium is reached = solutions on either side of the membrane are isotonic. Hypertonic = above strength (undiluted). Hypotonic = below strength (diluted).

Osmosis Osmosis is the diffusion of water across the cell membrane. Play video

Osmotic Pressure Organisms have to have a way to balance the intake of water. Because a cell is filled with salts, sugars, and proteins and other molecules, it is hypertonic to fresh water. This will cause water to fill the cell until it is filled. Won’t always burst because 1. Body cells are in isotonic fluids. 2. Single-cell organisms have a protective cell wall.

Facilitated Diffusion Does not require energy from the cell. Membrane allows material across the membrane driven by diffusion. Protein channels are tunnels that allow material to be passed through. Play video

Active Transport Protein pumps actively move material across the cell membrane; requires energy from the cell. Endocytosis: cell takes in material by enfolding itself around it. Phagocytosis: extensions of cytoplasm surround a particle and package it within a food vacuole. Pinocytosis: like endocytosis, but with liquid. Exocytosis: removal of water/materials from cell using a contractile vacuole. Play video

Levels of Organization Atoms  Molecules/compounds  organelles  Cells  Tissues  Organs  Organ Systems  organism Cells begin as blank slates (unspecialized- STEM CELLS) and then become specialized; they get specific jobs.