Unit 3: The cells

Hierarchy of structure( least to most complex)

• Atom
• Molecule
• organelle
• cell
• tissue
• organ
• organ system

Atom

• Smallest unit of matter
• Ex: Hydrogen, oxygen, nitrogen, carbon

Molecule

• Multiple atoms bonded together
• Ex: water, carbohydrates, proteins, lipids, nucleic acids, ATP

Organelle

• Small structures that make up cells
• Ex: mitochondria, nucleus, ribosomes

Cell

• Basic unit of life; made of organelles all working together

Tissue

• Group of connected cells that work together to function
• Ex: connective tissue, epithelat tissue, nervous tissue, muscle tissue

Organ

• Two or more tissues that work together to function
• Ex: brain, heart, lungs, skin, kidneys

Organ system

• Two or more organs that work together to function
• Ex: skeletal system, muscular system, digestive system, respiratory system

Robert Hooke

• Made up the term cell and looked at core plants

Leeuwenhoek

• Made microscopes

Mattias Schleiden

• Cells make up every part of the plant

Theodor schwann

• Knew animals are made of cells

Cell theory

• All living things are made of cells
• basic unit of structure and function in organisms
• cells come from other cells

Cells have:

• Cell membrane
• cytoplasm
• cytoskeleton
• ribosomes
• DNA

Cell membrane

• Surround the cell ;seperate the inside from the outside
• controls what enters or leaves the cell
• selective: does not let everything pass through
• semi- permeable: allows most liquids through
• made of 2 layers: the phospholipid bilayer
• parts- phospholipids and proteins

Cytoplasm

• Everything that is inside the cell membrane but it is outside the nucleus

Cytoskeleton

• Fibers that give structure to the cell

Ribosomes

• Make proteins

DNA

• Genetic code for the cell

2 types of cell

• Prokaryotic
• Eukaryotic

Prokaryotic Cells

• Small and simple
• unicellular
• no nucleus
• no organelles
• cant carry out specialized functions
• long tail like structure that allows movement
• Ex: bacteria

Eukaryotic cells

• Complex
• unicellular or multicellular
• have nucleus
• have organelles
• Ex: plant cells, animal cells

Phospholipids

• Make up the cell membrane
• 2 parts
• —phosphate head: polar and hydrophilic- water loving
• —lipid tail: nonpolar and hydrophobic- water fearing

Proteins in the cell membrane

• - channel/ transport proteins
• - receptor proteins
• - enzymes
• - anchor proteins
• -glycoproteins

Channel proteins

• Help polar molecules move in and out the cell membrane
• Ex: sugar and salt

Receptor proteins

• Allow cells to communicate with eachother

Enzymes

• Help speed up chemical reactions inside or outside the cell

Anchor proteins

• Help maintain the cells shape
• stabilize the location of the cell

Glycoproteins

• Serve as identification tags that are recognized by other cells

Membrane transport

• Help with movement of substances across the cell membrane
• 2 forms:
• -passive
• -active

Passive transport

• Does not require energy
• particles move from HIGH TO LOW concentration
• 3 types
• -diffusion
• -osmosis
• -facilitated diffusion

Diffusion

• Movement of material from HIGH TO LOW concentration
• no energy needed
• no channel proteins needed

Osmosis

• Movement of water molecules from HOGH TO LOW concentration
• no energy needed
• no channel proteins needed

Applying Osmosis

• When a cell is placed in a solution with the same concentration nothing will happen this is called ISOTONIC SOLUTION
• when a cell is placed in a solution with a greater concentration of water, it SWELLS this is called HYPERTONIC SOLUTION

Facilitated Diffusion

• Movement of molecules from HIGH TO LOW concentration using channel proteins
• no energy needed
• channel proteins are needed

Active transport

• Movement of molecules from LOW TO HIGH concentration using energy
• requires both energy and channel proteins

Endocytosis

• Movement of a substance into a cell by a vesicles
• cell membrane forms a vesicle around the substance and closes up and pinches afterward

Exocytosis

• Movement of substances out of a cell through a vesicle

Cytoskeleton

• Protein fibers that help define the shape of a cell and give it shape
• 3 types
• -microfilaments
• -intermediate filaments
• -microtubules

Microfilaments

• Thinnest of the cytoskeleton
• found in most cells especially muscles- helps muscle contraction
• help determine the shape of the cell

Intermediate filaments

• Provide a frame for organelles can be held
• allows cell to run more efficiently

Microtubules

• Thickest type of cytoskeleton
• 2 functions
• -transportation
• -cell reproduction

Cytoplasm

• Region between the nucleus and cell membrane

Cytosol

• The semi fluid substance inside of the cell
• organelles can be found in the cytosol

Nucleus

• Controls the activity of the cell
• contains DNA

Nuclear membrane

• Seperates the nucleus from the cytoplasm
• regulates what enters and exits the nucleus

Nucleolus

• Found in center of nucleus
• makes ribosomes

Ribosomes

• Make proteins
• found in 2 places
• -cytoplasm
• -ER
• made in the nucleolus

Endoplasmic reticulum(ER)

• 2 types
• - ROUGH ER
• —has ribosomes
• —ribosomes on ER make proteins that are exported from cell
• - SMOOTH ER
• —makes lipids
• —break down carbohydrates
• —detoxifies drugs and poisons

Golgi apparatus

• Modifies , sorts, and packages proteins for secretion
• involved in transporting lipids around the cell
• involved in creation of lysosomes

The pathway out

• Proteins made on the Rough ER are usually exported from the cell
• Cytosol>ER>Golgi Apparatus>cell membrane>OUT

Lysosomes

• Vesicles that hold enzymes
• digest and recycle used cell parts
• without them we couldn’t break down cell parts

Mitochondria

• Site of cellular respirations
• converts sugar into energy

Chloroplasts

• Only in plant cells
• site of photosynthesis
• produce sugars for the cell

Vacuole

• Largest organelle in plant cell
• holds waste and other material
• when full makes plants rigid

Cell wall

• Outer covering of cell
• surrounds the cell membrane
• Functions
• -gives plant shape
• -protects the cell
• only in plant cells