Bio - 2-14 (Molecules and Cells)

Water acts as the link between ___ and ___ molecules

abiotic, biotic

Water is required for …?

1. Effective interaction of molecules, allowing growth and copying

2. Formation of compartments to allow the development of intended chemistry

Water chemical structure

1 oxygen atom covalently bonded to 2 hydrogen atoms

Electronegativity of H₂O?

Pair of electrons in covalent bonds NOT SHARED EQUALLY

Electronegativity def.

measures how strongly the nucleus attracts the shared electrons

Factors affecting electronegativity?

1. number of protons in nucleus

2. number of orbital levels in the atom

   a. more orbital levels = less pull on shared electrons due to more distance from nucleus

Oxygen is ___ electronegative than hydrogen

more

Which (H or O) has more attraction over the shared electrons?

O

Water as a polar molecule

electrons spend more time with oxygen thus the oxygen has a partial negative charge (DIPOLE)

Bonding between water molecules

• Partially + H is attracted to partially - O (of other molecules)

• Hydrogen bonds

• Indicated with dotted line in diagrams

• H-H bonds break + reform rapidly between H₂O and H₂O BUT polar covalent bonds break less fequently

Cohesion occurs when?

when ‘like’ molecules are mutually attracted

• ex. H₂O is highly cohesive bcs H-H between H₂O molecules

What happens during cohesion?

Pulls water molecules together and the forse of collision may counterfit gravity (ex. water droplet)

Capillary Action

occur when water is pulled through narrow tubes as a result of cohesion + adhesion

• ex. sands, soils, plants using to move H₂O into cell walls

Adhesion

The force of attraction between different types of molecules or substances

Hydrophilic

Molecules attracted to water (usually polar)

Hydrophobic

Doesn’t have a chemical attraction to water

Metabolism

A complex assortment of chemical reactions

Cytoplasm (metabolism)

aq solution where substates of metabolic reactions and catalysing enzymes dissolve, which allows cells to;

• control composition

• respond to envrionment

• maintain functions of life

ex. amylase + starch = glucose

Cells rely on ___ molecules for certain functions inc forming cell membrane barriers

hydrophobic

Cohesion + Surface tension

Molecules on the surface are pulled inward by cohesive forces, reducing the surface area.

Properties of water

• Thermal conductivity: ability to conduct heat (higher than air)

• Viscosity: how easily fluid can flow

• Specific heat capacity: absorbs and is able to distribute heat

• Buoyancy: upward force on an object in a fluid that opposes the weight (gravitational force)

Examples?

Cell theory states…

1. all living things are made up of cells

2. cells are the basic units of life

3. cells come from pre-existing cells

Characteristics of a light microscope

• Easy to use

• Living specimen

• Natural color of cell is shown

• Energy efficient

• 1500x magnification

• lower resolution (0.25mm-0.3mm)

Characteristics of a electron microscope

• non-living specimen

• black and white / stained

• electricity consuming

• 100-300k magnification

• higher resolution (0.001mm)

Immunoflourescence

Creates antibodies with flourescent stains to be able to see how antibodies work when targeting a specific antigen (proteins)

Cryogenic electron microscopy

to determine the structure of molecules in near-atomic-level resolution

freeze fracture electron microscopy

rapid freezing of cells —> fractured along the weak lines + center of membranes —> etch the surface with coating to create a replica —> view on electron micrography

graticule

unit for the scale seen in the lens of the micrograph, need to be calibrated with a standard stage spectrometer

steps to make a scale bar for biological drawings

1. calibrate size of 1 ocular unit (measure distance between 2 markings and calibrate against stage micrometer)

2. measure length of organism against microscope

3. determine length of organism in micrometers

4. draw organism + measure length of drawn organism

5. calculate values to draw scale bar (20% the length of the og. organism)

   1. (length of scale bar (microm)/length of organism (microm)) = (length of drawn scale bar/length of drawn organinsm)

1 m = 1000 mm

1 m = 1000 mm

1 m = ___ cm

1 m = 100 cm

1 mm = ___ micrometer

1 mm = 1000 micrometer

1 micrometer = ___ nanometer

1 micrometer = 1000 nanometer

1 nanometer = ___ pm

1 nanometer = 1000 pm

What do all cells contain?

1. DNA / Genetic Material

2. Cytoplasm composed of mainly H₂O

3. Plasma membrane made of lipids that encapsulate cell content

4. Ribosomes

Flagellum in PR cells are for

circular movement

Flagellum in EU cells are for

vertical movement (waveish)

Plasma Membrane / Cell Membrane

• seperating interior from exterior

  • a bilayer formed from phospholipids

    • due to hydrophobic and hydrophilic regions

  • prevents too much water getting inside (bcs flooding = burst)

Survival of a species relies on _____ ________

genetic variation

Prokaryotic cell (DNA)

• A single loop of DNA, referred to as 'naked' due to it not being assocaited with histone proteins

• stores the information necessary for synthesising proteins

Eukaryotic cell (DNA)

• tightly wrapped around histone proteins (tightly coiled because keeping hidden = less likely to mutate)

• contained in the cell’s nucleus,

• molecule that carries genetic information for development and functioning of an organism

Free Ribosomes

• located in the cytoplasm

• make proteins that remain inside the cell’s cytoplasm and used inside the cell

bound ribosomes

• attached to cytosolic side of the endoplasmic reticulum

• proteins producesd end up inside the lumen of the RER and then exported for use outside of the cell

• more numerous in the cell than free ribosomes (bcs produce proteins for use in the body)

EU Ribosomes

80s

PR Ribosomes

70s

Case Study; RBC’s

• dont have DNA or nucleus bcs they need space for O2 and hemoglobin —> maximising the space

• break down every 120 days hence dont carry genetic information

pancreas, insulin, ribosomes

• pancreas’ endocrine (horomone production) function produces insulin that regulared blood G levels

• ribosomes translate mRNA into polypeptides + proteins and synthesize mRNA for insulin to create insulin proteins

Prokaryotic Cells

• unicellular organisms NOT containing membrane-bound organelles

• contains free ribosomes 70s (protein synthesis)

• Bacteria and Archea (single celled organism like bacteria) are types of PR

Components of a Prokaryotic Cell

• Cell wall; outside the cell membrane, protecting PR cell against external toxins, resists high osmotic pressure, maintains shape of cell

• Plasma membrane; seperates the int. to ext., controls what exits + enters (phospholipids)

• Cytoplasm; water-based, jelly-like, suspends ions, organic molecules, DNA, ribosomes, site of metabolic reactions

• Naked DNA; found in nucleoid, not associated with histone proteins

• 70s ribosomes; smaller than EU ribosomes, translation occurs

• Plasmid; small pieces of DNA tranferable from one PR cell to another, (horizontal gene transfer)

• Polysaccharides; outer layer protecting organism, allows adherence

• Flagellum; locomotion, spinning to propel cell through its medium (sperm)

• Pili; protein filaments on cell wall aiding in cell adhesion + DNA transfer (increased surface area)

Components of a Eukaryotic Cell

• Cell wall; outside the cell membrane, protecting PR cell against external toxins, resists high osmotic pressure, maintains shape of cell

• Plasma membrane; seperates the int. to ext., controls what exits + enters (phospholipids)

• Cytoplasm; water-based, jelly-like, suspends ions, organic molecules, DNA, ribosomes, site of metabolic reactions

• Mitochondria; double-membrane bound organelles that convert glucose —> ATP through respiration

• 80s ribosomes (bound + free); where translation occurs, bound w ER

• Naked DNA in a loop; not associated with histone proteins, double membrane with pores for certain molecules to pass (G, RNA, etc.)

• Smooth ER: Produces + stores lipids

• Rough ER: ribosomes attatched = proteins for outside cell

• Golgi apparatus; processes + packages proteins —> released to golgi vesicles

• Vesicle: small sac transporting + releasing substances through fusing with cell membrane

• Vacuole: maintains hydrostatic/osmotic balance, stores substances (ex. water)

• Cytoskeleton; system of protein fibres called microtubles + microfilaments (to hold organelles in place + cell structure)

• Lysosomes: compartments that break down + recycle waste

Eukaryotic Cells

• contains a nucleus and is membrane bound with cytoplasmic organelles

• some are multicellular, huge diversity of cells

• Compartmentalised organelles

EU Cells: Compartmentalisation

• contain membrane-bound organelles (ex. mitochondria)

• allows for interior of organelle to have separate conditions than the ext.

• PROS;

  • higher concentrations of substances

  • seperates toxins (ex. enzymes) from other parts of cell

  • controls internal conditions of for optimal enzymatic functions