IB Bio: Cellular Biology

7 functions of all living things

Metabolism, Growth, Reproduction, Response, Homeostasis, Nutrition, Excretion

Homeostasis

process by which organisms maintain a relatively stable internal environment

Cell Theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

SA:V ratio

the surface area to the volume ratio gets smaller as the cell gets larger, therefore the cell becomes less efficient.

Villi

Tiny finger-shaped structures that cover the inner surface of the small intestine and provide a large surface area through which digested food is absorbed

Microvilli

projections on villi that increase surface area

Organism Hierarchy

cell, tissue, organ, organ system, organism

Emergent Properties

the result from the arrangement and interaction of parts within a system
(ex. muscle cells --> cardiac tissue contracts --> heart pumps blood --> blood moves through circulatory system --> whole organism uses blood), is not visible in an individual component

cell differentiation

the process by which a cell becomes specialized for a specific structure or function. This involves expression of specific genes and not others

stem cells characteristics

self-renewal ability, Potency for differentiation

totipotent stem cells

can grow into any other cell type and extra-embryonic tissue, fertilized egg

pluripotent stem cells

Stem cells that can become almost all types of tissues and cells in the body, embryonic stem cells

Blastocyst

hollow ball of cells, forms 5-6 days after conception

multipotent stem cells

can grow only into cells of a closely related cell family, adult stem cells

This element is in most macromolecules. Why?

Carbon, It has 4 potential bonds

Macromolecules

carbohydrates, lipids, proteins, nucleic acids

Carbohydrate base equation

CH2O

Glucose

C6H12O6

Monomer

small chemical unit that makes up a polymer

Carbohydrates provide _____________ energy

short-term

Enzymes

Proteins that speed up chemical reactions by lowering activation energy (breaks apart more efficiently)

Lipids provide long-term energy ______

storage

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic phosphorous head and a nonpolar, fatty-acid hydrophobic tail.

intramolecular attraction

attraction within a molecule, H bonds, Ionic bonds, Covalent bonds, Van Der Wall forces.

intermolecular attractions

attractions between molecules, H bonds

Holds Phospholipids with embedded proteins

H bonds

Phospholipid head made of...

glycerol, phosphate and choline / two phosphate groups

phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes.

amphipathic

having both a hydrophilic region and a hydrophobic region

molecules that CAN move through phospholipid bilayer

Hydrophobic molecules (O2, CO2, N2, steroids) and small uncharged polar molecules ( H2O, glycerol, ethanol, urea)

Molecules that CAN'T move through phospholipid bilayer

Large uncharged polar molecules (Glucose, sucrose) and ions (Na+, K+, Ca2+, Cl-)

concentration gradient

H-->L

L-->H requires ___

ATP

Fatty Acid tails are held together by

weak hydrophobic interactions

Davson-Danielli model

• model of the cell membrane in which the phospholipid bilayer is between two layers of protein

• Based on an e^- microscope image of a trilaminar appearance, suggested proteins flank phospholipid bilayer

• Assumed uniform thickness of membranes and constant lipid: protein ratio, does not show permeability

• Falsified: the temperature at which membranes solidify does not correlate with this model, freeze fracturing and splitting membrane showed irregular rough surface (transmembrane proteins); fluorescent antibody tagging showed proteins are mobile

fluid mosaic model

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

role of cholesterol in plasma membrane

• maintains membrane fluidity through extreme temps by immobilising outer surface

• reduces permeability to small water-soluble molecules

• Has an amphipathic character

Cholesterol is not in the cell membrane of _____ cells

plant

integral membrane proteins

completely penetrates the bilayer, amphipathic

peripheral proteins

bound to the surface of the membrane

peripheral proteins function

• Cell-to-cell links and recognition, provide support on the intracellular surface, and form part of glycocalyx (slime capsule),

• anchors carbohydrates (glycoproteins)

• Signal transduction - receptors for peptide hormones

• Site of enzyme activity

Cell-cell recognition uses _____ and ____.

glycoproteins, glycolipids

protein channels

a type of integral protein in the membrane whose role is to pass molecules that cannot go through the membrane

passive transport

the movement of substances across a cell membrane without the use of ATP by the cell

simple diffusion

solute diffuses through cell membrane

facilitated diffusion

The use of a protein channel or carrier proteins to move through cell membrane. Used for large and/or polar molecules and ions

carrier proteins

uses glycoproteins to bind to specific solute and change shape to shuttle them across the membrane

rate of diffusion:
Increased temperature

increased rate of diffusion

rate of diffusion:
decreased molecular mass

increased rate of diffusion

rate of diffusion:
increased cell membrane thickness

decreased rate of diffusion

rate of diffusion:
Increased SA:V

increased rate of diffusion

Hypotonic Solution

Isotonic Solution

Hypertonic Solution

Osmolarity

measure of solute concentration

hyperosmotic

high solute concentration (low water concentration), water moves in

hypoosmotic

low solute concentration (high water concentration), water moves out

High concentration of ________ in intercellular environment of almost all human cells

Potasium

High concentration of ________ in extracellular environment of almost all human cells

Sodium

Outline the steps of the Sodium Potassium Pump

- 3 NA+ Ions bind to the protein
- Phosphorylation occurs, the ATP loses one of its 3 phosphates, creating ADP
- This causes the protein to change shape and expel the NA+ ions
- 2 K+ ions bind to protein, causing it to release its phosphate
- protein returns to original shape, expelling K+ ions

Endocytosis

Membrane surrounds a substance and brings it into the cell be forming a vesicle

phagocytosis

Type of endocytosis, brings in molecules to make phagosomes

Phagosome

Vesicle containing molecule, in cytoplasm, comes from phagocytosis

pinocytosis

process by which certain cells can engulf and incorporate droplets of fluid, creates vesicles

Exocytosis

Golgi Apparatus packages secretory vesicles to be excreted by the cell

Three challenges to the cell theory

-Striated muscle fibres have multiple nuclei
-Aseptate Hyphae have no cellular partitions
-Giant algae is made from a single cell

cytoplasm

internal fluid of cell, contains nutrients

Nucleoid

In prokaryotic cells, the part of the cytoplasm that has DNA

Genophore

In prokaryotic cells and mitochondria, circular DNA

Plasmids

In prokaryotic cells, autonomous circular DNA molecules that can be transferred during conjugation. They can replicate by themselves.

lysis

bursting of a cell

Cell wall of prokaryotes made of

peptidoglycan

Purpose of the slime capsule

prevents drying out (desiccation) and phagocytosis by another cell

Slime capsule is made of ______

polysaccharide layer

Pili

Hair-like extensions, can be used for attachment to surfaces and bacterial conjugation

Bacterial conjugation

Joining of two cells in preparation for the transfer of DNA (plasmids) from one to the other

Flagella

Tail like extension, has motor protein enabling movement

Grainy appearance in electron micrographs caused by...

large numbers of ribosomes

Binary fission

• Similar to mitosis but for prokaryotes and simpler

• Circular DNA copied, two DNA loops attach to the plasma membrane

• Cytokinesis occurs

Chloroplasts

Only in plant cells and algae cells. Contains its own DNA and Ribosomes and a double membrane, meaning it likely came into the cell by endosymbiosis. Involved in photosynthesis

Thylakoids

Flattened sacs that absorb light.

Grana

A stack of thylakoidd

Stroma

Surrounds the grana, has enzymes and chemicals needed for photosythesis

cytosol

the aqueous part of the cytoplasm within which various particles and organelles are suspended

Endoplasmic Reticulum

network of channels extending throughout the cell, transports materials inside cell

Rough ER

"Workbench" of Ribosomes, where they synthesize protein. Closer to the nucleus

Smooth ER

has enzymes on its surface. Its functions are making membrane phospholipids and cellular lipids, production of sex hormones, detoxification of drugs in liver, storage of calcium ions (needed for muscle contraction), transports lipid-based compounds, helps liver release glucose into bloodstream

ribosomes

no exterior membrane, protein synthesis, composed of a type of RNA and protein, larger and denser in eukaryotes

Lysosomes

processed by golgi apparatus, single membrane surrounds many hydrolytic enzymes -acidic environment necessary for hydrolyzation, breaks down old/damaged organelles, breaks down material from phagocytosis

Hydrolytic Enzymes

break down macromolecules into basic monomer units

Golgi Apparatus

responsible for collection, packaging, modification, and distribution of materials synthesized in cell. Products of ER move through cis side, cisternae, then out trans side as vesicles.

Cisternae

flat sacs that make up the ER and golgi apparatus

Glandular Cells

cells that secrete substances, have many vesicles

mitochondria

an organelle containing enzymes responsible for producing ATP (adenosine triphosphate), has double membrane, the inner membrane is folded into crista which increases the surface area

Nucleus

contains DNA in the double membrane nuclear envelope, membrane has pores for communication

Nucleosome

eight histones wrapped with a strand of DNA and secured with a ninth H1 histone

Nucleolus

area in nucleus where ribosomes are made

many highly specialized cells do not have ______ and therefore cannot reproduce

nuclei

Microtubules

centrioles assemble them, they make up mitotic spindles

Centrosome

small region of cytoplasm adjacent to the nucleus; contains the centrioles and serves to organize the microtubules