Biology: Levels of Organization

General Biology

• Biology is the study of life and living organisms, and their structure, function, growth, evolution, distribution, and environmental interactions
• A biologist studies life from different angles

Levels of Biological Organization

• Atoms represent the smallest unit of an element composed of neutrons, protons, and electrons
• Molecules are formed through the union of two or more atoms
• Cells are the structural and functional units of life
• Tissues represents groups of cells with similar structure and function
• Organs consists of tissues performing specific tasks together
• Organ systems are multiple organs working together
• Organisms are individual, complex entities with organ systems
• Species refers to groups of similar organisms that can interbreed
• Population refers to organisms of the same species inhabiting a specific area
• Ecosystems are communities interacting with their physical surroundings
• Biosphere represents regions of the Earth's crust, waters, and atmosphere inhabited by living organisms

Cell Biology

• Cells are the basic unit of life
• Organisms can either be unicellular (single-celled) or multi-cellular (many cells)
• Cytology is the study of a cell's structure, behaviour and function
• Schleiden, Schwann, and Virchow proposed the cell theory
• The key principles of cell theory are:
  • All living things are composed of cells
  • Cells are the basic units of life in terms of function and structure
  • All cells come from pre-existing cells

Types of Cells

• Prokaryotic cells are simple, small, and lack a nucleus, as well as membrane-bound organelles
• Bacteria and archaea are examples of prokaryotic cells
• Prokaryotic cells contain a circular DNA molecule inside the nucleoid region
• Prokaryotic cells contain ribosomes, a plasma membrane, and a cell wall, and in some instances, they possess a capsule or flagella
• Eukaryotic cells are larger, more complex, and possess a nucleus and membrane-bound organelles
• Animals, plants, fungi, and protists are eukaryotic
• The DNA in eukaryotic cells is safeguarded within the nucleus
• Eukaryotic cells can be either unicellular or multicellular

Cell Organelles and Their Functions

Common to Plant and Animal Cells

• Nucleus: regulates cell activities and contains DNA
• Ribosomes: facilitates proteins synthesis
• Endoplasmic Reticulum (ER):
  • Rough ER: protein synthesis due to the presence of ribosomes
  • Smooth ER: responsible for lipid synthesis and detoxification because it lacks robosomes
• Golgi Apparatus: modifies, packages and sorts proteins and lipids
• Mitochondria: produces ATP through cellular respiration
• Cytoplasm: fluid that supports organelles
• Plasma Membrane: regulates the passage of substances in and out of the cell
• Lysosomes: they break down waste using digestive enzymes

Specific to Plant Cells

• Chloroplasts: facilitate photosynthesis; contain chlorophyll
• Cell Wall: made of celluose; protects and provides structure
• Central Vacuole: maintains cell pressure; stores water, nutrients and waste

Specific to Animal Cells

• Centrioles- They help with cell division (mitosis and meiosis).
• Lysosomes- Frequently found in animal cells, they break down cellular waste and debris

Cellular Energetics

• Cellular energetics refers to the mechanisms cells, acquire, store, and utilize energy
• Energy supports cellular functions like homeostasis, movement, and growth
• Adenosine Triphosphate (ATP) is the key energy currency of the cell

Enzymes and Metabolism

• Metabolism: Represents the sum of every chemical reaction in an organism
  • Catabolic pathways: breakdown molecules and release energy, such as during cellular repsiration
  • Anabolic pathways: Consume energy and build molecules, for example in photosynthesis
• Enzymes: biological catalysts accelerate chemical reactions by lowering activation energy
  • Key factors that affect the activity of enzymes include pH, temperature, inhibitors, and substrate concentration

ATP: The Energy Currency of the Cell

• ATP consists of ribose, adenine, and a trio of phosphate groups
• A great amount of energy is stored in ATP's very energetic phosphate bonds
• ATP is hydrolyzed to ADP+Pi to release energy
• ATP is regenerated via photosynthesis and cellular respiration

Photosynthesis: Energy Conversion in Plants

• Photosynthesis: converts glucose; transforms light energy into chemical energy
• This process happens in the plant cell's chloroplasts

Stages of Photosynthesis

• Light-dependent reactions: using light energy, these reactions occur in the thylakoid membrane and produce ATP and NADPH, while splitting water and releasing oxygen
• Calvin cycle: these reactions occur in the stroma by utilizing ATP and NADPH to transform CO2 into glucose

Cellular Respiration

• Cellular respiration: cells extract energy from glucose via this process
• Aerobic respiration results in 36-38 ATP, requires oxygen
• Anaerobic respiration/fermentation results in 2 ATP, doesn't require oxygen

Stages of Cellular Respiration

• Glycolysis(occurs in the cytoplasm): creation of 2 ATP and 2 NADH molecules; glucose is broken down into 2 molecules of pyruvate
• Krebs cycle (citric acid cycle): (occurs in the mitochondria): yields 2 ATP, CO2, NADH and FADH2
• Pyruvate is converted into Acetyl-CoA
• Electron transport chain(ETC): ( occurs in the mitochondrial membrane): generates about 34 ATP through oxidative phosorylation

Fermentation (Anaerobic Respiration)

• This occurs when oxygen is unavailable. Two types:
  • Lactic acid fermentation (occurs in muscle cells yielding 2 ATP and lactic acid)
  • Alcoholic fermentation (occurs in yeast cells yielding 2 ATP, CO2, and ethanol)

Cell Cycle and Cell Division

• Cell cycle: cells undergo events as they grow and split and is composed of main stages:
  • interphase stage: cell grows and replicates DNA
  • mitotic Phase: this is where cell division occurs

Phases of Cell Cycle

• Interphase represents the longest phase, and possesses 3 subphases:
  • G1 phase (gap 1): DNA prepares for replication, cell grows, and organelles duplicate
  • S phase (synthesis) identical genetic material is ensured to be in each doaghter cell, and DNA replicates
  • G2 phases (gap 2): mitosis is prepared for and the cell further grows
• Mitotic(M) phase has division of the nucelus(mitosis) and two daughter cells result as the cytoplasm divides causing(cytokinesis)

Mitosis: Stages of Nuclear Division

• Mitosis makes sure every daughter cell gets the exact copy of the parents DNA, plus has 4 primary phases
  • Prophase: nucelar membranes break down, while spindle fibers form and chromatin condenses into chromosomes
  • Metaphase: alignment chromosomes align at the cell's equatorial plate
  • Anaphase: pulled apart to cells opposite pole, sister chromaids
  • Telophase: nuclear membranes form along around the separated chromosomes, plus are decondensed

Cytokinesis

• Cell membranes pinch inward(cleavage furrow) resulting is split cytoplasm in animal cells
• Cell plate makes mew celll wall in plant cells

Meiosis: Formation of Gametes

• Type from which cell division lessens chromosome numver by half, and ultimately 4 genetically original haploid cells result.

Meiosis I and II

• Prophase I consists of homologous chromosomes where crossing over and synapsis occurs to exchange gentetic material
• Metaphse I involves homologous chromosome pairs aligning along the elquator
• Anaphase I is when to homologous chromosomes seperate and flow through opposite poles
• Two hapliod cells are formed in Telophase I and Cytokinesis
• Prophase II is when chromosomes condense and spindle fibers reform
• In metaphase II Chromosomes align along the elquator
• Anaphase II where they seperate, sister chromaids
• Four gentetically unique haploid cells result in Thelophase II and Cytokinesis

Divison of cells Importance

• Mitosis enables growth plus development in organisms
• Damaged cells get replaced through tissue repair and replacement because of mitosis
• Meosis makes for a sexual production in gamets
• Meisosis introduces gentic divison with it in the crossing over and independent assortment

Regulation of Cell Cycle

• Cell cycle check points are put in place to ensure proper cell divison (G1, G2, M check points)
• The cell cycle is regulated with Cyclins and CDKs(Cyclin dependent kinases)
• Uncontrolled cell growth is prevented by programmed death(Apoptosis)
• Mutations result in unregulated cell division causing cancer

Biomolecules

• Essential for life they're referreds as organic moelcules
• Have main types being Nucleic Acids, Proteins, Lipids, and Carbohydrates
• Primarily formed with nitrogen, phosporus, carbon, oxygen and hydrogen

Carbohydrates

• The make organic combinations from carbon, hydrogen and oxygen (1:2:1)
• The primary source of cellular energy
• Structural ingredients in chitin and cellulose (arthropods and plants)

Types of Carbohydrates

• Monosaccharides
  • Quick energy source and single sugar units
  • Galactose, Fructose, Glucose
• Disaccharides
  • Formed through dehydration synthesis
  • Maltose (Glu+Glu) Lactose (Gal+Glu), Sucrose (Fru+Glu)
• Polysaccharides
  • Cellulose, chitin glycogen, starch
  • Long chains via monosaccharides that store energy and make up structure

Lipids

• Hydrophobic non polar molecules not soluble in water
• Cell membrane structure, insulation, protection and long term structure

Types of Lipids

• Fats and Oils/Trigylcerides
  • Made witg faty acid threesome and one glycerol unit
• Saturated fats
  • Solid room temp
  • Example: lard and butter no double bonds
• Unsaturated fats
  • Fish and olive oil: examples made with one or more double bonds
  • Liquid room temp
• Phosolipids
  • Composed of
  • Glycerol
  • Phospate group
  • Two fatty acids
  • The cell membranes bilayer compnent
• Steroids
  • Four fused rings of of carbon to support cell membrane balance and hormonal signaling
  • Cholestrerol, Estrogen, Testosterone
• Protective coatings in animals and plants
  • Waxes

Proteins

• Built throguh amino acids with bond peptides
• Response with immune response, movement, enzymes, strucutre, and transport

Structure of Proteins

• Sequnece of amino acids and primary structure Seconday Structure
• Alpha helix + beta pleated sheath 3 Dimension folding
• 3D folding due to interactions between R-groups
• Multiple polypedtide chaings result in quaternary structure

Types of Proteins

• Enzymes
  • Increase from chemical reactions for example lactase + anaylase
• Strucutral Protiens
  • Provide support
  • Collagen, keratin
• Transport Proteins
  • Hold molecules
  • Hemoglobin like blood
• Hormonal Protiens
  • Regulate by biological processing
  • Insulin
• Defense Proteins
  • Immune response
  • Antibodies

Nucleic Acids

• Information genetically stored and carried
• Include sugar, nitrogenous base, phosphate group

Types of Nucleic Acids

• DNA
  • Deoxyribose like sugar
  • Thymine, guanine, adenine, cytocine; Bases
  • Stores genetic codes double stranded
• RNA
  • Single stranded involoveds in protien synthesis
  • Uracil, guanine, adenine, cytosine
  • Sugars Like ribose
• ATP
  • Supplies ribose
  • Triphosphate threesome with adenine for containing cells energy

The Central Dogma of Molecular Biology

• Info flows inside a biological framework according to CMMB dogma.
  • Proposed 1958 via Francis Crick
  • It express how genetic information flows from RNA to to DNA to proteins.

Core Processions from CMMB Molecular Biology

• Ensures proper codes from division of cells.
  • Nucleus in Eukaryotes and Cytoplasm in prokaryotes
• DNA replication through
  • ligase: brings Okazaki fragments with lagging strand
  • Polymerase: creates new DNA strands.
  • Helicase: unbinds double helix

Transcription to RNA

• Procedure for RNA synthesis from DNA.
  • Starts inside cytoplasm and ekarytoes nucleus of prokaryotes.
• Steps including RNA creation
  • Ribosomes contain genetic code
• mRNA(messenger RNA) holds genetic code

Genetic Code and Codons

• Nucleotides that compose triplets via codes like those.
  • AUG in (Methionine)
  • UAG,UAA, UGA stop for codons

Regulation of Gene Expression

• Regulated via translational, transcriptional, post, translational, and post
• Elements regulated are...
  • Promoters: sequences of for creating code
  • Enhancers + sileners increase plus decrease efficiency for coding
  • Operons: regulating genetics like Ecoli

Mutation plus effects

• Mutation alters central dogma by changing DNA sequences
  • point mutations (substitution, insert, delete
  • Silent and nonsense Mutations The Three Plant Systems' roles are

Plant and animal systems

• All plant systems make a difference in these systems roles:
• Guard against plants via dermal protection with cuticle plus epidermis
• Through transporting nutrients with vascualr, the xylem for carrying minerals from roots to sleeves along with phloem for transporting sugars/minerals in a plant

Plant System

Support plus storage via photosynthesis and includes collencyham+sclerenchyma+ parenchyma.

Plant Organs

• They sustain life through...

The 3 plant system jobs are for -Root System - Abosorbed plant, mineral, and water.

• Shoots like stems leaves etc make productional seeds happen,
  • through reproduction

Animal Plant System

The five keys with functions that work that have 5 are those:

• Digestive for energy that breka down using intestine + liver)
• Respiratory exchanges gases using mammals lungs and gills as fish are
• Nervous (controls bodies with neuron activity and spinal cord)
• Excertrory System
  • For removing kideny or waste through bladders

Animal Reprodcution

• There are two kinds as such
• For Budding. parthenogenesis via aezual reproduction with fragment
• Fertilization and gamete is made with delevopment

In Animals

• Balancing waters, temp and internal environments
• Animals adapt in different behavioral +structural physiological ways

The Two Important Systems

• Active transport needs energy while passives does not.
• Concentration drives movement of molecules for transport and cellular membranes allows it

For Simple Diffusion

• Through membranes from high to low levels Example) CO2 plus 02 dispersion in longs

Secondary Active transport

Glucose from carreir protiens happens through facilitated dispersion

Cell to cell: Osmosis and Endocyotis

Cellular life depends on the diffusion of molecules across different selective membranes

• molecules moves high to low solutes
• A cells water shifts depend on tonic soltuions

Solutions

These tonics result depending molecules and it is :

• isotonic
• Hypotonic
• Hypertonic