Cell Structure and Function

Cell Theory 

• all living things are made of cells

• cells are the basic unit of life

• all cells come from prexisitng cells

Prokaryotic cells

Small cells with no nucleus or membrane-bound organelles (DNA floats in cytoplasm)

Eukaryotic cells

Larger cells with a nucleus and membrane-bound organelles

Peptidoglycan

A rigid structural molecule found in bacterial cell walls

What do prokaryotic and eukaryotic cells have in common?

• Cytoplasm

• DNA

• Ribosomes

• Cell membrane of phospholipids and proteins

Semipermeable

Allows some substances to pass but blocks others

Diffusion

The movement of molecules from high concentration to low concentration without energy

Simple Diffusion

Small, uncharged molecules (like gases) moving directly across the cell membrane (no energy required) 

Osmosis

Diffusion of a water across a semipermeable membrane

Isotonic

Solute concentration is the same inside and outside the cell (water flows in and out of the membrane at the same rate) 

Hypotonic

Solution outside the cell had fewer solutes —> water enters the cell and it swells up (more solutes inside)

Hypertonic

Solution outside the cell has more solutes —> water leaves the cell and it shrinks shrink (less solutes inside) 

Transport Proteins

Proteins that help substances move across the cell membrane

Facilitated Diffusion

Passive transport (no energy) using channels or carriers to move substances across the membrane (high to low)

Active Transport

Movement of substances against the concentration gradient (low to hight) using energy (ATP) and pumps

Whats the difference between channels, carriers, and pumps?

• channels and carriers = passive (no energy)

• pumps = active (need energy)

Nucleus

Organelle containing DNA,

• transcription occurs here

• surrounded by a double membrane

• pores for transport

Transcription

The process of makeing RNA from DNA

Endoplasmic Reticulum (ER)

Organelle near the neucleus

• makes proteins and anything that need to be exported from the cell

Rough ER

Ribosomes that make proteins

Smoother ER

Makes lipids, detoxifies cells

Golgi Apparatus

A stack of membranes that modifies, sorts, and packages proteins received from the ER for transport to specific locations

Lysosomes

Organelles full of digestive enzymes that break down worn out parts of the cell and materials from the environment

Vesicles

Small membrane-bound sacs that transport and store substances within a cell

Endomembrane System

Cell organelles that make, package, and transport proteins and lipids 

• Rough ER → makes proteins

• Smooth ER → makes lipids

• Golgi apparatus → modifies, sorts, and packages

• Vesicles → transport materials

• Lysosomes → break down waste

Cytoplasm

Gelatinous aqueous interior

Ribosomes

A complex of RNA and protein that carry out protein synthesis (look like tiny dots: found on rough ER and scattered in the cytoplasm)

Mitochondria

• extract energy from food

• double membrane

Chloroplasts

• sunlight to energy 

• double membrane 

• specific to photosynthetic eukaryotes

Cytoskeleton 

Network of protein fibers that help with:

• cell support

• cell movement

• movement of structures within cells 

Endosymbiosis Theory 

The idea that organelles formed by a eukaryotic cell eating another 

How does penicillin function?

Blocks cell wall synthesis, creaking a holey cell wall (can’t make peptidoglycan)

Competitive Inhibition

The mechanism for blocked the normal function of a protein

Gram-Positive 

Peptidoglycan in cell wall retains the Gram stain 

Gram-Negative

• Lipid outer layer of cell wall doesn’t have gram

• Penicillin can’t reach the peptidoglycan

What cell components contain DNA?

• mitochondria

• nucleus

What things are shared by all organisms?

• DNA

• Cytoplasm

What cell components are present in both plant and animal cells?

• mitochondria

• ER

• ribosomes

• Golgi

• mitochondrion

• lysosome

Why can oxygen diffuse across biological membranes?

Oxygen can diffuse across biological membranes because they are small and non-polar