Cell Parts Flashcards
Overview: fundamentals of cells
- All organisms are made of cells
- the cell is the simplist colle4ction of matter that can be alive
- Cell structure is correlated to cellular function
- All cells are related by their descent from earlier cells
Why do we use microscopes
Scientist use microscopes to visualize cells too small to see with the naked eye
Light Microscope (LM)
- Visible light is passed through a specimen and then through glass lenses
- LMs can magnify about 1000 times the size of the specimen
What can and cant you see through a LM?
- Can see: Can see: nucleus, chloroplasts, maybe mitochondria
- Can’t see: Most subcellular structures, including organelles
Electron Microscope (EM)
- Used to study subcelluolar structures
- Scanning Electron microscopes
- Transmission electron microscopes
Scanning electron microscope (SEMs)
- Focus a beam of electrons onto the surface of a specimen providing imagines that look 3-D
- Outer view
Transmission Electron microscope (TEMs)
- Focus a beam of electrons through a specimen
- Used to study the internal structure of cells
- Do this by slicing what you are looking at
Cell Fractionantion
Takes a cell apart and seperates the major organelles from one another
Whats a centrifuge?
Fractionate cells into their component parts so scientists can determine the functions of organelles
Basics of ALL cells
- plasma membrane
- semifluid called cytosol
- Chromosomes (carries genes)
- Ribosomes (makes protiens)
Prokaryotic cells
- No nucleus
- DNA is an unbound region called the nucleoid
- No membrane-bound organelles
- Cytoplasm bound by the plasme membrane
Eukaryotic cells
- DNA in a nucleus that is bounded by a membranous nuclear envelope
- Membrane-bound organelles
- Cytoplasm is the region between the plasme membrane and nucleus
Plasme membrane (cell membrane)
- Selective barrier that allows passage of oxygen, nutrients and waste
- General structure is a phospholipid bilayer
Wheer is the eurkaryotic cells genertic instruction housed?
In the nucleus and carreid out by ribosomes
The nucleus
- Contains most of the cell’s genes
- usually the most conspicuous organelle
- Information central
Nuclear envelope
- Encloses the nucleus
- Seperates it from the cytosol
Nuclear lamina
- Maintains the shape of the nucleus
- Composed of protiens
Chromosomes
Discrete unites DNA is organized into
Chromatin
DNA and protiens of chromosomes together
Nucleolus
Located within the nucleus and is the site of robosomal RNA synthesis
Ribosomes
- Protien factories
- PArticles made of ribosomal RNA and protien
- Carry out protien sythesis in two locations; the cytosol, or on the outside of the endoplasmic recticulum or nuclear envelope
Endomembrane system
- Regulates protiens traffic and performs metabolic functions in the cell
- The components of the endomembrane system are either continuous or connected via transfer by vesicles
Components of the endomembrane system
- Nuclear envelope
- ER
- Golgi apparatus
- Lysosomes
- Vacuoles
- Plamsa membrane
Endoplasmic Recticulum
- Accounts for more than half of the total membrane in many eukaryotic cells.
- ER membrane is continuous with the nuclear envelope
- Two distinct regions; Smooth ER and Rough ER
The smooth ER
- synthesizes lipids
- Metabolizes carbohydrates
- Detoxidies drugs and poisons
- Stores calcium ion
- No protien functions because no ribosomes
The Rough ER
- Has bound ribosomes, which secrete glycoprotiens
- Distributes transport vesicles, protiens surrounded by membranes
- Is a membrane factory for the cell
What is a glycoprotien
Protiens covalently bonded to carbohydrates
The Golgi apparatus/bodies
- consists of flattened membranous sacs called cisternae
Functions of the golgi apparatus
- Modifies products of the ER
- Manufactures certain macromolecules
- Sorts and packages materials into transport vesicles
Lysosomes
- Membranous sac of hydrolytic enzymes tthat can digest macromolecules
- Use enzymes to recycle the cells own organelles and macromolecules; autophagy
Lysosomal enzymes
- Hydrolyze protiens, fats, polysaccarides, and nucleic acid
- Work best in acid environments inside the lysosome.
Phagoctosis
- When a type of cell englufs another cell thus forming a food vacuole
- A lysosomes fuses with the food vacuole and digests the molecules
Vacuoles
A plant cell or fungal cell may have one or several vacuoles, amde from endoplasmic recticulum and Golgi apparatus
Types of vacuoles
Food vacuoles, contractile vacuoles, central vacuoles
Food vacuoles
Fromed by phagocytosis
Contractile vacuoles
- Found in many freshwater protist
- Pump extra water out of cells
Central vacuoles
- Found in many mature plant cells
- hold organic compounds and water
Mitochondria
- Sites of cellular respiration
- In nearly all eukaryotes
- Smooth outer membrane and an innder membrane folded itno cristae
Chloroplasts
- Found in plants and algae
- sites of photosynthesis
- Contain green pigments chlorophyll as well as enzymes and other molecules that function in photosynthesis
- one of a group of organelles called plastids
Evolutionary similarities between Mitochondria and Chloroplasts
- mitochondra and chloroplasts are similar to bactera
- Both are enveloped by a double membrane
- Contain free ribosomes and cirular DNA molecules
- Grow and reproduce womewhat independently in cells
Endosymbiont theory
- An early ancector of eukaryotic cells engulfed a non pohotosynthetic prokaryotic cell which formed an endosymbiont relationship with its host.
- The host cell and andosymbiont merged into a single organism (eukaryotic cell with mitochondrion)
Mitochondrial matrix
- Is the inner membrane creates two compartments, mitochondrial matrix and intermembrance space.
- Some metabolic steps of cellular respriation are catalyzed here
Cristae
Present a large surface area for enzymes that synthesize ATP
Structures of chloroplasts
Thylakoids and Stroma
Thylakoids
Membranous sacs, stacked to form a granum
Stroma
Internal fluid
Peroxisomes
- Specialized metabolic compartments bounded by a single membrane
- produce hydrogen peroxide and convert it to water
- Help perform reactions with many different functions
Cytoskeleton
- Helps to support the cell and maintain its shape
- Interacts with motor protiens to produce motility
- Organzies cells structures and activitites
- Anchors many organelles
3 main types of fibers that make up the cytoskeleton
Microtubuals, microfilaments, intermediate filaments
Microtubuals
- Thickest out of the three
- hallow rods
- 25mm in diameter
Functions of microtubules
- shaping the cell
- guiding movement of organelles
- Seperating chromosomes during cell division
Microfilaments
- Also called actin filaments
- Thinest
- solid rods about 7nm in diameter
- built as a twisted double chain of actin subunits
Intermediate filaments
- Diameter in a middle range
- 1-12 nm in diameter
- solid with many strands
Centrosome
- Microtubulas grow out from a centrosome near the nucleus
- Known as a microtubule-organzing center
Centriole
In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring
Cilia and Flagella
Microtubules control the beating of cilia and flagella
Common structures cilia and flagella share
- A core of microtubules sheathed by the plasma membrane
- A Basal body that anchors the cilium or flagellum
- A motor protien called dynein, which drived the bending movements
