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1665 -- ___________ discovered cells by observing cork and called them “cells”
Robert Hooke
1674 – ________________ observed microorganisms in pond water (each cell had a “central part”
Anton van Leeuwenhoek
Mid 1800’s – work by ________, _______, & ________ is used to develop the cell theory – all plants and animals made of cells and all cells come from other cells
Schleiden, Schwann, & Virchow
What is the Cell Theory (2 things)
Cells are the basic units of structure and function in all living things, New cells come from existing cells
Prokaryotes
simple cells that DO NOT have a nucleus (archaebacteria & eubacteria)
Eukaryotes
complex cells that have a nucleus and membrane bound organelles (protists, fungi, plants, & animals)
Nucleus
Function:
1. Directs activities of the cell due to nucleotide sequence
Like making proteins to carry out cell processes.
2. Houses the DNA (genetic material)
Found in all eukaryotic cells
First identified by botanist Robert Brown
Surrounded by a porous nuclear envelope with nuclear pores
Houses the nucleolus
Nucleolus
A dense (dark) region inside the nucleus that contains DNA and RNA.
Function: Makes both the protein and RNA portions of ribosomes
Chromatin / Chromosomes
Structure inside the nucleus that contains the DNA
Called chromatin when the cell is not dividing and called chromosomes when the cell is dividing and the chromatin is wrapped around proteins called histones.
Function: Contain and organize DNA to be passed to new cells
Cytoplasm/Cytosol
Cytoplasm – all material between the cell membrane and the nucleus, including organelles
Cytosol - Jelly-like fluid that surrounds the organelles – 80% water
Function: Solution that allows transportation within the cell & provides an environment for the organelles
Plasma (Cell) Membrane
Phospholipid bilayer with embedded proteins and marker glycoproteins
(glycol – relating to formation of a sugar)
Forms a flexible barrier between the cell and its surroundings
Function: Controls what enters and leaves the cell (Selectively Permeable)
Golgi Apparatus
It consists of six or seven flattened membrane sacs
Discovered by Camillo Golgi
Function: To collect and package proteins and lipids modified in the ER
Cis face
closest to endoplasmic reticulum and receives proteins from the ER
Trans Face
furthest from ER and closer to membrane since many proteins are shipped out of the cell
Mitochondria
It is a double membrane organelle
The inner membrane is folded to increase surface area
Only organelle that contains its own circular DNA and replicates independently
Function: Release energy stored in glucose/oxygen molecules to produce ATP (adenosine triphosphate) during cellular respiration
Endoplasmic Reticulum (ER)
The ER is an extensively folded, internal membrane
Connects to the nuclear membrane
Primary site of protein translation (making protein from RNA)
Function: Assembles, modifies, and transports cellular products (proteins/enzymes/lipids) throughout the cell
Rough ER
Contains ribosomes
Processes the proteins (folds and carries) made by ribosomes
Smooth ER
Transports compounds around the cell
Processes fats and breaks down toxins in the liver
No ribosomes
Ribosomes
Small bodies made up of RNA and proteins
Found free in the cytoplasm or attached to the Rough ER
Function: Make proteins - site of amino acid chain building that then fold to become proteins
Cytoskeleton
Crisscrossed network of proteins fibers
1. Microtubules – hollow tubes of protein
2. Microfilaments – long, thin protein fibers
Function: Supports the shape of cells and anchors its organelles
Centrioles
Found only in animal cells
Made of bundled microtubules
Part of the cytoskeleton
Function: Helps organize cell division by orienting the spindle fibers and poles of the cell for cytokinesis
Vacuole
Function:
Stores water, sugars, salts and proteins
Provides pressure (turgor pressure) for support in plant cells
Sac-like structures
Usually large in plant cells and smaller and more numerous in animal cells
LYSOSOMES
Lysosomes are spherical organelles in the cytoplasm.
They contain digestive enzymes.
Function: They digest and recycle used components of the cell/ cell invaders
Peroxisomes
Membrane-bound organelle where certain enzymes (such as catalase) are used to break down compounds such as H2O2 and detoxify the cell.
Special type of Lysosome
Function: Digests fatty acids & gets rid of the waste product, hydrogen peroxide
Cell Wall
Found in plants, algae, fungi, and bacteria
Surrounds the plasma membrane
Function: Support & Protection
Chloroplasts
Found only in plants and some algae and protozoans
Contains the green pigment called chlorophyll in thylakoids which are stacked together and called granum
Function: Helps plants to produce their own food by converting the energy from sunlight into glucose (photosynthesis)
Chromoplasts
Plastids that contain pigments other than chlorophyll
Not found in animal cells
Function: Responsible for flower and fruit color
Cilia
Hair-like structures that are smaller and more numerous than flagella
Not all cells contain these.
Function: Locomotion – moving the entire cell or for moving substances past the cell
Flagella
Long, whip-like structures
Composed of bundled microtubules that project from the cell’s surface
Not all cells contain a flagellum.
Structure of the plasma membrane
The plasma membrane is a double layer of phospholipids
They form a very flexible barrier
Phospholipid Bilayer
The heads of the molecule are polar (hydrophilic – likes water)
Face outward and form the outside of the plasma membrane
The fatty acid tails are nonpolar (hydrophobic –do not like water)
Face inward and form the middle of the plasma membrane
The heads of the molecule are _____ (hydrophilic – likes water)
Face outward and form the outside of the plasma membrane
polar
The fatty acid tails are ________(hydrophobic –do not like water)
Face inward and form the middle of the
plasma membrane
non polar
selectively permeable
it only allows certain materials to pass through the membrane
There are proteins embedded in the plasma membrane that serve as:
1. channel proteins
2. marker proteins,
3. receptor proteins
Channel Proteins-_________________________________
Like tunnels
serve as passageways to transport substances across the membrane
Marker Proteins-__________________
Kind of like a white flag to immune system cells
identify and distinguish cells
Receptor Proteins- ______________________________________
sends signals to the cell from messenger molecules outside the cell
Solvent ________________________________
The part of the solution that does the dissolving
Water is the universal solvent
Solute
______________________________________________
The part of the solution that is being dissolved
May be a solid, liquid, or a gas
Passive
The cell does not use energy to transport substances
Diffusion
Osmosis
Facilitated diffusion
Active
The cell must use energy to transport substances
Protein pumps
Bulk transport
Diffusion
Molecules move from an area of high concentration to an area of low concentration until molecules are evenly dispersed (equilibrium)
Occurs due to Brownian Motion-the constant, random movement of all molecules
Concentration Gradient
The difference in concentration of a substance across a space
The greater the difference the faster diffusion occurs
Temperature
Higher temperatures make the molecules move faster and speed up diffusion
Facilitated Diffusion
Diffusion of substances through a membrane with the aid of transport proteins
The substance is still moved from high to low concentration so no energy is used (passive transport)
Glucose enters cells through facilitated diffusion
Osmosis
The diffusion of water molecules through a selectively permeable membrane
Low concentration of solution to high!
Isotonic Solution
There is an equal concentration of water inside and outside the cell
Water moves in and out of the cell at equal rates
There is no net change in the cell
Hypotonic Solution
Hypo = below (low)
Lower concentration outside the cell.
The water will move into the cell
The cell will swell and could rupture if it takes in too much water
Hypertonic Solution
Lower concentration inside the cell.
The water will move out of the cell
The plasma membrane will shrivel up
Hypotonic: Lysis
when an animal cell has ruptured due to water entering the cell
Hypotonic: Turgor Pressure
the expanding of the cell membrane in a plant cell due to water entering the vacuole.
Hypertonic: Crenation
the shrinking of the cell membrane in an animal cell
Hypertonic: Plasmolysis
the shrinking of the cell membrane in a plant cell
Protein pumps
The substance uses a protein located in the plasma membrane to pass through the membrane
The substance moves from low concentration to high concentration
These pumps transport only a specific type of substance
Bulk Transport
substances are too large to pass through the membrane channels
Endocytosis
the plasma membrane surrounds the particle and encloses it in a vacuole
Phagocytosis –endocytosis of solids
Pinocytosis – endocytosis of liquid
Exocytosis
the reverse of endocytosis
Waste particles that are too large to pass through the membranes are expelled by exocytosis