Bio 10 🧬🔬🧫

Spontaneous Generation/Abiogenesis

The belief that life could arise from non-living matter; proposed by Aristotle

Characteristics of Living Things

• Made of cells

• Need energy

• Produce wastes

• Responds and adapts to their environment

• Reproduce

• Grow

Biogenesis

The development of living organisms from other living organisms.

Level of organization

Cells (most basic) → Tissues →Organs → Systems (most complex)

Cell

• The most basic unit of structure and function

• all living things are composed of cells

• cells are OPEN-SYSTEMS

Tissue

• A group of similar cells that share the same structure and function

• Ex: muscle tissue, nervous tissue, epithelial tissue, connective tissue (in human); vascular tissue (in plants)

Organ

• A group of various types of tissues that work together to perform a specific function

• Ex: brain, heart, leaf

System

• A group of organs and tissues that perform a shared complex function

• Ex: digestive system

Multicellularity/ Multicellular Organisms

An organism consisting of many cells of different type (ex: human)

• have a larger size

• have a variety of specialized cells

• have an ability to thrive in a broader range of environments

• Individual cells in a group organize themselves and interact with each other to function efficiently

Cell Theory

1. All organisms are composed of one or more cells
2. The cell is the smallest functional unit of life
3. All cells are produced from other cells

Francesco Redi

Italian physicist that disproved the theory of spontaneous generation

Experiment: In 1668, he placed meat in two different jars. He covered one jar with cloth and left the other open. While maggots developed in the open jar, none appeared in the covered jar.

Louis Pasteur

French scientist who was convinced spontaneous generation did not occur and disproved it by observing micro-organisms multiplying under a microscope.

-Invented pasteurization: heat is applied to kill microbes and prevent spoilage and disease.
-Proved the "active principle" in air was also an organism through the "swan-neck flasks" experiment

Rudolf Virchow

German physician who concluded that cells divide to produce more cells.

—> cell comes from other living cells

Robert Hooke

An English scientist who was the first to name the structures he saw under a microscope as "cells".

Antony van Leeuwenhoek

• a Dutch tradesman and scientist became the first person to look at living cells

• He increased the resolution and magnification of microscopes

Zacharias Jansen

A Dutch lens maker who was credited with forming the first compound light microscope

Matthias Jakob Schleiden + Theodor Schwann

• German scientists

• Schleiden concluded all plants are composed of cells and that each new cell developed from the nucleus

• Schwann found that animal cells are also made up of cells

Compound Light Microscope

A microscope with two or more lenses (typically the ocular lens and objective lenses) that is used to view objects illuminated by visible light.

Most biological material is transparent, compound microscope allow for contrast by adding stain

Parts of a Compound Light Microscope

Tube, Revolving Nosepiece, Objective Lenses (low, medium, high), Stage Clips, (Iris) Diaphragm, Lamp/Light Source, Eyepiece/Ocular Lens, Arm, Stage, Coarse Adjustment Knob, Fine Adjustment Knob, Base

Tube

Connects the eyepiece to the rest of the the microscopes

Revolving Nosepiece

Rotates/ revolves to change the objective lenses

Objective Lenses

• Low (4X), Medium (10X), High (40X)

• Used to view objects at three different magnifications

Stage & Stage Clips

• Stage: the platform that supports the slide being viewed

• Stage clips: hold the slide in place

Iris Diaphragm

Adjust the amount of light entering the field of view (FOV)

Lamp/Light Source

Provides light to illuminate the object

Ocular Lens/Eyepiece (10X)

Look through this to see an object under the microscope

Arm

connects the base and the barrel

Base

support the microscopes

Fine Adjustment Knob

• Moves the stage a very small amount up and down to bring the object into focus.

• Used on medium and high objective lenses

Coarse adjustment Knob

• Moves the stage up and down, which brings the object into focus.

• Used for LOW power

Organelles

• “Little organs” in a cell with a specific function

• Maintain life: acquire nutrients, excrete waste, exchange matter and energy

3 main types of cells

Plant, Animal, Bacteria

Total Magnification

Tells us how magnified the object is.
Formula: Total mag. = ocular lens x objective lens

Field of View (FOV)

It's the area seen when looking in a microscope.

• Formula: Mag on High/Mag on Low = Field Dia on Low/Field Dia on High

• FOV can be referred to as field diameter

• increase the magnification, the field of view gets smaller

Size of Specimen (Actual Size - AS)

• An approximation of the size of the specimen viewed

• Formula: SOS/ AS = FD x fraction of space occupied by specimen

Prokaryotes

• single-celled organisms with no nucleus (prokaryotic) and no membrane-bound organelles

• 2 domains: archaea and bacteria

• contain: ribosomes, flagella, some nuclear materials, some prokaryotes have cell walls

• Ex: cyanobacteria, E. coil bacteria, thermophiles

• are very small (smaller than eukaryotes)

• Found almost everywhere (soil, skin, intestines,…)

• Interior is entirely cytoplasm, with some ribosomes

• Nucleoid is the space where ribosomes are

• Chromosomes/ DNA are usually circular

• Reproduce by binary fission

eukaryotes

• Complex cells with an organized nucleus, many membrane-bound organelles

• Can be single/ multi-celled

• Ex: animals, plants, human

Systems

• open system: allow the exchange of both matter and energy

• closed system: allow the exchange of energy but not matter

• isolated system: allow neither

Organelles in animal cell

• Cell membrane

• Cytoplasm

• Nucleus + Nucleolus

• Rough/ Smooth ER

• Ribosomes

• Vesicles

• Golgi Apparatus

• Lysosomes

• Centrioles

• (Cytoskeleton)

Organelles in plant cell

• Cell wall

• Cell membrane

• Cytoplasm

• Nucleus + Nucleolus

• Rough/ Smooth ER

• Ribosomes

• Large central vacuole

• Golgi Apparatus

• Chloroplast (chlorophyll)

• (Cytoskeleton)

Cell Membrane (plasma membrane)

The boundary around a cell that separates the cell interior from the environment.

• consists of a double membrane structure

• made of phospholipids, proteins, carbs, cholesterol

• control cell transport (what in + out of cell)

• Semi-permeable, in both plant and animal

Cytoplasm

Jelly-like fluid inside a cell including all organelles except the nucleus

• Mostly made of water + hold organelles

• in both plant and animal cells

Nucleus

Acts as the "control center" in a cell

• Contain nucleolus, nuclear envelope, nuclear pore, chromatin

• contains genes/ genetic info

• directs the structure and function/all activities of the cell.

• in both plant and animal

Nucleolus

The area in the nucleus of a cell where ribosomes are produced.

Ribosomes

The cell structure that translates genetic information sent from the nucleus into proteins

• can be free floating in cytoplasm or attached to the rough ER; made of 2 subunits

• Synthesizes (builds) proteins from DNA, using amino acids

• In both plant and animal

Lysosomes

A vesicle containing digestive enzymes (a type of protein) where materials and old cell parts that no longer work are degraded to be recycled or used to provide energy

• “clean up crew”

• animal cells ONLY

• The pH is generally low, helping the digestive enzymes function

• Lysosomes can fuse with vesicles containing food particles

• Some lysosomes protect the body by killing infectious micro-organisms

Endoplasmic Reiticulum (ER)

A network of folded membranes and tubes connected with the nucleus, where proteins and lipids are synthesized and packaged in vesicles.

• Rough: attached ribosomes; transports proteins.

• Smooth: without ribosomes; produce, transport, metabolize lipids and hormones (usually send to the cell membrane/ the Golgi apparatus)

• Both in animal and plant

Golgi Apparatus/Body

Where proteins and lipids from the endoplasmic reticulum are modified, repackaged, and distributed to other locations in the cell

• Both in animal and plant

• Major role: folding and packing proteins

• Also produce lysosomes

Mitochondria

the "powerhouse", where food molecules are broken down into ATP energy that can be used by the cell to carry out other activities

• Converting sugar into ATP (adenosine triphosphate) = cellular respiration

• in both plant and animal

Centrioles

located near the cell nucleus; helps organize genetic material during cell division

• in animal cells, most plant cells don’t have them

• When a cell divides, it must reproduce all of its genetic material and then divide this material between the two new cells

• During cell division, centrioles help by moving genetic material correctly into each new cell

Vacuoles / vesicles

A balloon-like organelle that can store water, food, and minerals in a cell

• Both in animal and plant

• Animal cells have many smaller vacuoles AKA vesicles

• Plant cells have a large central vacuole

  • store mainly water + maintain the shape of plant cell

  • can contain poisons to prevent animals from eating the plant

• Some vacuoles contain wastes

Cell Walls

Very thick layer made of cellulose (fiber) that surrounds the cell membrane of plant cells

• provide structure + support

• prevent over-expansion when plants take in water

• ONLY plant cells

Chloroplasts

containing chlorophyll, where photosynthesis takes place (plants making glucose)

• ONLY plant cells

• Have two layers of membranes: an inner layer of flattened membrane sacs enclosed by a second outer membrane

• The inner membranes contain the green pigment molecule chlorophyll

Chlorophyll

A green pigment found in chloroplasts that traps light energy for photosynthesis

Glucose

A sugar that is used by cells as a source of energy

formula: C₆H₁₂O₆,

Photosynthesis

The process by which plants use light energy, water, and carbon dioxide to produce food (sugars) in the form of carbohydrates and oxygen.

• carbon dioxide + water + (sunlight)→ oxygen + glucose

• 6 CO2 + 6 H2O + (sunlight) → 6 O2 + C6H12O6

• Occurs in the chloroplasts; chlorophyll traps sunlight

Cellular Respiration

The process by which cells obtain energy by breaking down glucose in the presence of oxygen.

• both plant and animal cells

• requires mitochondria

• sugar (glucose) + oxygen → carbon dioxide + water + ATP

• C₆H₁₂O_{6 (aq)} +6 O_{2 (g)} → 6 CO_{2 (g)} + 6 H₂O _(l)

Surface Area-to-Volume Ratio

• Cells want a high SA and low V = high SA:V ratio

• skinner, flatter and smaller cells absorbs and excrete substances/ nutrients more efficient → functions better

• (ex: microvilli in small intestine, cilia)

• Volume increases faster than SA, as a cell grows

• Large and complex organism must be MULTICELLULAR

• When a cell can no longer function well → it divides

Cell differentiation

• All cells in the multicellular organism have the same sets of genes

• But large differences in structure and activities

• Not only have genes for the instructions of their functions but also to specialize in every possible way

Nutrients that enter the cell

• Glucose

• Water

• Hormones

• Minerals (ions)

• Oxygen

Wastes that cells need to remove

• Urea (protein breakdown)

• Excess water

• Excreted hormones + enzymes

• Minerals (ions)

• CO2

• Lactic acid

Particle Model of Matter

1. All substances are made out of tiny particles

2. All particles in a pure substances are the same

3. Particles are in constant, random (Brownian) motion

4. There are attractive forces of varying strength between particles

5. There are spaces between particles, which can be occupied by particles of other substances

Solute

something that dissolves in a solvent

• usually a solid, grams

• the lesser amount/ minor component of a solution

Solvent

substance that dissolves a solute

• usually a liquid, litres

• the greater amount/ major component of a solution

Solution

solute + solvent

concentration

number of molecules in a solution per litre (g/l)

concentration gradient

difference in concentration between 2 areas

Permeability

• Impermeable: don’t allow any solute to pass through

• Semi-permeable: allow some solutes through but block others (cell membrane)

• Permeable: allow any material to pass through

Selectively permeable membrane

a barrier that allows only certain solutes, based on

• size

• shape

• electrical charge

• lipid solubility

• Ex: oxygen-in, CO2-out

Fluid Mosaic Model

describe what the cell membrane looks and functions like

• Mosaic: a pattern of different types of molecules put together

• Fluid: the movement of the membrane, floating around not static

Phospholipid bilayer

• phosphate heads: hydrophilic (water-loving), polar

• lipid tails: hydrophobic (water-fearing), non-polar

• water do not seep in and out of the cells due to water-fearing tails

• lipid and lipid-soluble substances can pass through

Cholesterol

controls the fluidity of cell membrane, “stabilizer”

• in cold → keeps the lipids moving so that they don't freeze

• in hot → it slows the lipids down, limiting their travelling

carbohydrate chains

• attached to the lipids/ proteins outside of the cell membrane

• act as "cell markers" or signs so that the immune system knows the condition of cells

• involved in cell-to-cell communications

membrane proteins

• Embedded in the cell membrane

• transport certain substances/molecules through the membrane + carry out chemical reactions

• Some have "marker" molecules on them to allow cellular recognition + protect cells from infection.

• may also act as an attachment site for "messenger molecules” (hormones)

Messenger molecules

Used in cell-to-cell communication and control of cell functions (ex: hormones)

membrane proteins (positions)

Integral proteins: go through the membrane, transport water and water soluble substances

Peripheral proteins: only one side, can have enzymes (to speed up reactions) or cytoskeleton structure (to provide strength for the cell)

membrane proteins (functions)

transport proteins: facilitated diffusion (channel proteins, high→low), active transport (pumps, low→high)

* transmembrane/ integral protein

glycoproteins: identify cells that belong to an organism, cell recognition and signaling, have carbohydrate chains attach to them

*can be integral or peripheral

transport proteins

Channel protein (facilitated diffusion)

• create hydrophilic holes to transport molecule, some are “gated” (can open and close)

• have polar and non-polar parts

• transport molecules faster

Carrier protein (facilitated diffusion/pump)

• can change shape to move the molecules from one side of the membrane to another

• transport slower bc have to change shape + “reset” each time

• ex: glucose carrier, sodium-potassium pump

Cell transport

Passive transport (high→low, require no energy)

• Facilitated Diffusion

• Regular Diffusion

• Osmosis

Active transport (low→high, require energy)

• Protein pumps

• endocytosis

• exocytosis

toward/ up the concentration gradient

high → low

against/ down the concentration gradient

low → high

Regular/ simple Diffusion

some nonpolar molecules can pass through cell membrane by themselves (ex: oxygen, carbon dioxide)

Facilitated diffusion

• for molecules that can’t pass through the cell membrane on their own

• requires transport protein

• ex: glucose carrier, polar molecules

Osmosis

the diffusion of water across a membrane

high solute concentration = low water concentration → solute takes up room, leaving less space for water

active pumps

• a transport protein use ATP energy to move materials in/ out of cell

• ex: sodium-potassium pump

endocytosis (“endo” = in)

• requires ATP energy,

• cell membrane fuse with the substances → fusing substances usually will form vesicles around them → to bring them inside the cell

(vesicles are made out of the same material with the cell membrane → so it can be taken inside the cell)

Types:

• pinocytosis: cell drinking (take in a fluid/ liquid)

• phagocytosis: cell eating (take in a solid)

• receptor-mediated endocytosis: bind to substances

Receptors

• Proteins protruding from the cell membrane

• detect specific compounds or cells in their environment.

Exocytosis (“exo” = out)

• requires ATP energy

• allow substances to exit the cell

• Golgi Apparatus (pack stuff) → vesicles → cell membrane

Factors affecting the rate of diffusion

1. Temp (warmer = faster)

2. Pressure (more particles = faster)

3. Agitation (Stirring)

4. Size of solute (smaller = travel faster)

Tonicity

describe the amount of solute in a solution

3 types of solutions

• Isotonic (equal concentration)

• Hypertonic (higher concentration)

• Hypotonic (lower concentration)

Isotonic

• two solutions separated by a membrane that have equal concentration of solute

• water content/ mass stays the same

hypertonic & cell shrinking

• one solution has a higher concentration of solute

• ex: salty water

• Plasmolysis = cell shrinking (cytoplasm pull away from cell)

• both plant and animal cells will lose water content/ mass → shrivel/ shrink

• plant cells lose turgor pressure when placed in a hypertonic solution

hypotonic & cell swelling

• one solution has a lower concentration of solute

• cell will gain water content/ mass when placed in hypotonic solution

• Cytolysis = cell bursting

• plant cells don’t burst bc they have cell walls → so they require hypertonic solution

• animal cells can burst → so they require isotonic solution

Equilibrium

• A state in an isolated chemical system in which the net flow/ overall distribution does not change

• occurs once molecules are distributed evenly.

• Molecules do not stop moving after reaching equilibrium

Leaf-cross structure

• Mesophyll (middle layer): palisade, spongy

• Upper and Lower Epidermis

• Waxy Cuticle

• Guard Cell

• Stoma (stomata)

• Veins: xylem, phloem

Palisade Mesophyll

• long, narrow column-shaped cells packed closely together

• located near the top of the leaf for max light exposure

• contain the most chloroplasts

Spongy mesophyll

• round cells, few chloroplasts

• lots of space (air pockets) for gas exchange

Upper & Lower Epidermal Tissue

• Tightly interlocked, transparent cell layer → transparent to allow light through

• prevents physical damage, water loss

• protects from diseases by making the cuticles

Waxy cuticle

• made by epidermal cells

• prevents water loss via transpiration

• also acts as a defense against pathogens

• hydrophobic → water droplets stay on the leaf instead of soaking in

guard cell

control the opening and closing of the stoma