TEST 5 - CELLS Flashcards
Autotroph
Organisms that can make its own food
Heterotroph
Organisms that cannot make their own food.
Differentiate
- The ability of multicellular organisms to have cells that specialize in a certain function.
- Specialized Cells have switched on particular genes that correlate to these specific functions.
Cell Theory Principles
- All living things are made out of cells
> Multicellular
> Unicellular - Cells are the smallest units of life
> Carry out metabolic functions
> Cell components cannot survive alone - Cells come only from other cells
> Multiply by division
> Descended from simpler common ancestors
Functions of Life
Metabolism
Growth
Reproduction
Response
Homeostasis
Nutrition
Excretion
Ultrastructure
Detailed cell structures observable only under an electron microscope, such as organelles like ribosomes or the endoplasmic reticulum.
Micrograph: A photographic image captured using a microscope, often enhanced with color for clarity in presentations.
Light Microscope
- Magnifies up to 1,000x.
- Limited resolution due to the wavelength of visible light (400–700 nm).
- Can observe live specimens.
Electron Microscope
- Uses electron beams for higher magnification and resolution (up to 1,000,000x).
- Visualizes subcellular structures like organelles.
- Cannot be used on living specimens.
Staining
Techniques using dyes to highlight specific cell structures, such as methylene blue for DNA or fluorescent markers for proteins.
Cryogenic Microscopy
A method where proteins or molecules are frozen and imaged to create 3D models, ideal for studying their structure.
Freeze-Fracture Microscopy
A technique where frozen cells are fractured along membranes to visualize internal surfaces, such as transmembrane proteins
Cell Diversity
- Size: Ranges from microscopic bacteria to large egg cells.
- Shape: Adapted to function, e.g., nerve cells are elongated for signal transmission. (Coccus, Bacillus, Spirilla)
- Internal Organization: Variability in organelle presence and arrangement depending on the cell type.
Surface Area to Volume Ratio
- Determines the efficiency of material exchange.
- As a cell grows, its volume increases faster than its surface area, reducing efficiency.
- Smaller cells maintain faster diffusion, effective waste removal, and adequate nutrient absorption.
Emergent Properties
Complex functions arise when specialized cells work together in tissues, organs, and systems, enabling multicellular organisms to perform more than the sum of their parts.
Totipotent Stem Cells
Have the potential to develop into any cell type, including an entire organism, e.g., a fertilized egg.
Pluripotent Stem Cells
Can become almost any cell type in the body, e.g., embryonic stem cells.
Multipotent Stem Cells
Limited to forming specific types of cells, e.g., BLOOD, SKIN.
Unipotent Stem Cells
Specialized to form only one cell type, e.g., NERVE
Prokaryotic Cells
Simple, single-celled organisms without membrane-bound organelles, e.g., bacteria.
Prokaryotic - Slime Capsule
A protective polysaccharide layer that enhances survival in harsh conditions.
Prokaryotic - Cell Wall
Provides structure and protection, composed of peptidoglycan
Prokaryotic - Cytoplasm
Fluid containing enzymes for metabolic reactions.
Prokaryotic - Naked DNA
Circular genetic material not enclosed in a nucleus.
Prokaryotic - Ribosomes (70s)
Small ribosomes for protein synthesis.
Prokaryotic - Flagella
Tail-like structures for movement.
Prokaryotic - Pili
Hair-like structures for adhesion or genetic material exchange (conjugation).
Binary Fission (Prokaryotic)
Asexual reproduction process dividing a single cell into two identical cells.
Prokaryotic METABOLIC Activity
Photosynthesis, Nitrogen Fixing, Fermentation
Prokaryotic - Mesosome
- Helps in cell division
- Increases surface area
- In Aerobic Bacteria: Holds respiration chain
- In photosynthetic bacteria: Holds photosynthetic pigments
Prokaryotic - Cell (Plasma) Membrane
- Controls passage of materials
- Semi permeable
Prokaryotic - Plasmid
- Small circular DNA chain
- Codes for synthesis of certain proteins
- Used in genetic engineering
Nitrogen Fixing
Convert Nitrogen from air to Nitrogen compounds
Fermentation
Bacterial convert lactose into lactic acid
Eukaryotic Cells
Complex cells with membrane-bound organelles, found in multicellular organisms: ANIMAL, PLANT, FUNGAL
Eukaryotic - Cell Membrane
Structure:
- Composed of a phospholipid bilayer with embedded proteins.
- Contains cholesterol for added rigidity.
Function:
- Acts as a selectively permeable boundary between the cell and the external environment.
- Regulates the movement of substances into and out of the cell.
Eukaryotic - Nucleus
Structure:
- Spherical structure enclosed by a double membrane called the nuclear envelope.
- The envelope is porous, allowing the passage of proteins and ribosomes.
- Contains the nucleolus, where ribosomes are formed.
- Houses chromatin, which includes DNA and associated proteins.
Function:
- Storage center for the cell’s DNA.
- Directs cell activities by regulating gene expression.
Eukaryotic - Cytoplasm
Structure:
- Gelatin-like fluid found inside the cell membrane.
- Contains salts, minerals, and organic molecules.
Function:
- Serves as the medium where organelles are suspended.
- Site of numerous metabolic reactions.
Eukaryotic - Cytoskeleton
Structure:
- A network of thin, fibrous elements including microtubules (hollow tubes) and microfilaments.
Function:
- Provides structural support to the cell.
- Maintains the cell’s shape.
- Assists in cellular transport and organelle movement.
Eukaryotic - Centrioles
Structure:
- Composed of nine sets of triplet microtubules arranged in a ring.
- Found in pairs within a region called the centrosome.
Function:
- Play a major role in cell division (mitosis).
- Not present in plant cells.
Eukaryotic - Cilia and Flagella
Structure:
- Hair-like projections extending from the surface of cells.
- Cilia: Short and numerous.
- Flagella: Longer and fewer in number.
- Both are made of nine pairs of microtubules arranged around a central pair.
Function:
- Facilitate cell motility or the movement of fluids adjacent to the cell.
Eukaryotic - Basal Bodies
Structure:
- Anchor the microtubule assembly of cilia and flagella within the cell.
- Structurally identical to centrioles.
Eukaryotic - Ribosomes (80s)
Structure:
- Consist of two subunits made of protein and RNA.
- Found free-floating, in groups (polyribosomes), or attached to the rough ER.
Function:
- Site of protein synthesis in eukaryotic cells.
Eukaryotic - Endoplasmic Reticulum (ER)
Structure:
- A system of membranous tubes and sacs connected to the nuclear envelope.
- Forms transport vesicles.
- Two types: Rough ER and Smooth ER.
Function:
- Serves as an intracellular “highway” for the movement of molecules.
Eukaryotic - Rough Endoplasmic Reticulum (Rough ER)
Structure:
- Covered with ribosomes, giving it a rough appearance.
- Found near the nucleus.
Function:
- Prominent in cells that produce large amounts of protein.
- Synthesizes and transports proteins.
Eukaryotic - Smooth Endoplasmic Reticulum (Smooth ER)
Structure:
- Does not have ribosomes attached.
- Connected to the rough ER.
Function:
- Synthesizes lipids.
- Breaks down toxic substances.
Eukaryotic - Golgi Apparatus
Structure
- Stacked flat sachs
Function:
- Receives proteins from the rER and distributes them to other organelles or out of the cell.
Eukaryotic - Lysosome
Structure:
- Spherical organelles enclosed by a single membrane.
- Contain hydrolytic enzymes.
Function:
- Break down food particles, cellular debris, and invading pathogens.
- Aid in recycling worn-out cell parts.
Not commonly found in plant cells.
Eukaryotic - Peroxisome
Structure:
- Small spherical organelles enclosed by a single membrane.
- Contain enzymes for metabolic reactions.
Function:
- Break down hydrogen peroxide, a toxic byproduct of metabolism.
- Contribute to lipid metabolism and detoxification.
Eukaryotic - Mitochondria
Structure:
- Double-membraned organelle with inner folds called cristae.
- Contains its own DNA and 70s ribosomes.
Function:
- Converts energy stored in food into ATP through cellular respiration.
- Referred to as the “powerhouse” of the cell.
Secretory Pathway
rER packages protein into vesicles that separate from ER.
Transport Vesicles travel and fuse with the Golgi Apparatus.
Golgi modifies & repackages protein into new secretory vesicles.
Secretory Vesicles released into cytoplasm.
Vesicles fuse with Cell Membrane.
Contents released – SECRETION!
Fungal Cell
Cell Wall: Made of chitin (a carbohydrate).
Larger Food Vacuoles: Present in fungal cells.
No Centrioles: Unlike animal cells, fungal cells lack centrioles.
Not Photosynthetic: Fungal cells do not perform photosynthesis.
Plant Cell - Cell Wall
Structure: Rigid wall made out of cellulose, proteins, and carbohydrates
Function: Support
Plant Cell - Vacuole
Structure: sac of fluid surrounded by membrane
Function: Temporal storage
Plant Cell - Plastids
Three Types:
- Chloroplasts
- Chromoplasts: Synthesis and storage of pigments
- Leucoplasts: Store food just like starches, proteins, lipids
Plant Cell - Chloroplasts
Structure: Stacked sacs that contain chlorophyl
Contain DNA
Function: Photosynthesis
