General Biology Unit 1

Five Unifying Properties of Life

Growth & Development, Reproduction, Oder, Natural Selection, Regulation.

Reproduction

Organisms are able to reproduce and pass on their characteristics and traits to their offspring via the instructions encoded in DNA. 

Order

They exhibit order via their organs and organelles with specific functions. 

They are assembled from the same kinds of atoms, macromolecules, and cells. 

They are capable of processing energy and obeying the same **laws of energy.**

Natural Selection

Organisms adapt to their community via natural selection.

Regulation

Cells and organisms need to regulate their cellular activities in order to maintain homeostasis.

Hierarchical Levels of Biological Organisation

atoms - molecules - macromolecules - organelles - cells - tissues - organs - organ systems - organism - population - community - biosphere.

Definitions of Species

Morphological, Biological, Ecological, Phylogenetic.

Population

A species that interbreeds and lives in the same area.

Community

An interacting group of various species in a common location.

Biosphere

Portion of Earth inhabited by life.

Adenosine Triphosphate

A sugar, a nitrogenous base (adenine) and 3 phosphate groups. Energy currency used by cells, which store energy in their bonds.

Taxonomy

Domain - Kingdom - Phylum - Class - Order - Family - Genus - Species

Domain of Eukarya

Fungi, Plantae, Animalia, Protists

Biomass Pyramid

Chart showing the total amount of dry weight for each trophic level.

Pyramid of numbers

Chart showing the total number of individuals in a given ecosystem

Autotrophs

Depend on light energy and inorganic CHNOPS synthesizing their own macromolecules.

Heterotrophs

Depends on other organisms for their own energy and CHNOPS sources. Consumers + Decomposers.

Biomagnification

Refers to toxins that accumulate in higher energy levels, since toxins are hydrophobic and are not eliminated through excretion and decomposers.

Camouflage

Prey + predators show cryptic colorations to blend into their surroundings.

Batesian Mimicry

Prey mimics harmful species to frighten predators.

Mullein Mimicry

Noxious potential preys exhibit the same warning colorations as other species.

Essential Macromolecules for Life

Carbohydrates, Lipids, Proteins, Nucleic Acids

Metabolism

All cellular activities that take place in a cell.

Anabolism

Synthesis reactions, e.g dehydration synthesis.

Catabolism

Breakdown into smaller, simple components.

The properties of water are derived from…

Its hydrogen bonds (four at any given moment).

Emergent Properties of Water

Cohesion of Water Molecules, Moderation of Temperature, Floating of Ice on Liquid Water, Universal Solvent

Cohesion of Water Molecules

Water molecules stay close to each other despite changing arrangement : causes high surface tension (allows insects to walk on water) and capillary action.

Moderation of Temperature

Moderates the temperature in coastal areas, stabilizes the ocean’s temperature, regulates our temperature (evaporative cooling).

Floating of Ice on Liquid Water

When water freezes and becomes ice, its molecules are too slow to break its hydrogen bonds. 

Its hydrogen bonds keep molecules at a fixed distance, making ice less dense.

Allows aquatic organisms to survive winter.

Water : The Universal Solvent of Life

Water is unable to dissolve non-polar substances.

Evaporative Cooling

As a liquid evaporates, its surface cools down because its hottest molecules are the most likely to become gas.

Organic Compounds

Consist of 1+ elements of **H**, **O**, **N**, **P**, or **S**, covalently bonded to a **carbon** atom. Commonly form linear and ring-shaped backbones. **CHNOPS.**

Carbohydrates

CHO. Sometimes N, NEVER P. Most abundant macromolecules. Serve as fuel, chemical storage and structure.

Alpha Glucose

Fuel and chemical storage. Glycogen and Starch. OH group on the bottom.

Beta Glucose

Provide structural support. OH group on the top. Cellulose.

Lipids

NOT TRUE POLYMERS. CHON, sometimes P. Large group of hydrophobic molecules. Fats, phospholipids, steroids. Energy storage, structural support, body regulation.

Phospholipids

Contain phosphate. Primary components of cell membranes. Hydrophilic head and hydrophobic tail.

Fats

Large molecules assembled from smaller molecules. Consist of glycerol molecules joined to 3 or more fatty acids.

Unsaturated Fats

Double Bonds between carbons. “Kink” in structure, therefore liquid (vegetable oil). 1 fewer hydrogen bonds.

Saturated Fats

NO double bonds between carbons. No “kink” in structure, therefore solid (animal fats, butter). Maximum # of hydrogen bonds.

Steroids

Characterized by a carbon skeleton with 4 fused rings.

Proteins

CHNOS. Composed of monomers called amino acids joined via peptide bonds.

Function of Proteins

Enzymatic, Defensive, Storage, Structural, Transport, Hormonal, Receptor, Contractile

Amino Acids

Composed of an amino (N-H) group and a carboxyl (O-H) and a side chain.

Nucleic Acids

CHNOP. Composed of monomers joined by phosphodiester bonds. DNA and RNA.

DNA

Double helix, double stranded. Antiparallel and complementary. G, A, T, C. Stores genetic information.

Nucleotide

Basic building block of nucleic acids. Consists of a sugar molecule attached to a phosphate group and a nitrogenous base.

Purine

1 ring. Form hydrogen with pyrimidines to hold DNA together. Adenine and Guanine.

Pyrimidine

Form hydrogen bonds with purines. Cytosine and Thymine.

Promoter

Beginning sequence on a gene.

Terminator

End sequence of a gene, tells the RNA polymerase to stop transcription.

Messenger RNA

Carries information in the form of codons for the synthesis of proteins.

Transfer RNA

Carries and brings amino acids into position by binding its anticodon with a codon of mRNA.

Ribosomal RNA

Provides structure to ribosomes and catalyzes peptide bond formation between amino acids.

DNA Transcription

Synthesis of messenger RNA (mRNA), complementary to DNA template.

DNA Translation

Sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide. Has 3 stages : *Initiation, Elongation* and *Termination.* 

Why is the genetic code universal?

Universal The codons by which DNA’s instructions are translated into the same proteins by ALL organisms.

Why is the genetic code redundant?

Because there are many more codons than amino acids, most amino acids can be translated from 2 or more codons. Help protect against harmful effects from mutations.

Mutations

Permanent alteration in a gene’s base sequence. 

Cell

Smallest unit that retains the properties of life. New cells can only arise from pre-existing cells.

Lower Limit to Cell Size (1 micrometer)

Lack of space to contain all necessary space for life.

Upper limit to cell size (100 micrometers)

Surface to Volume ratio (square-cube law). As the volume increases the surface area is not large enough to allow efficient exchanges of the cell with its environment.

Pros of Light Microscopes

Can study living cells, can dye specific locations.

Cons of Light Microscopes

Lower resolution and magnification

Pros of Electron Microscopes

Better resolution and magnification

Cons of Electron Microscopes

Can only study dead cells.

Resolution

Minimal distance at which 2 points can be seen distinctly. The smaller the distance, the greater the resolution.

Components of the Minimal Cell

Cell Membrane, Cytoplasm, Ribosomes, DNA confined to one region.

Prokaryotic Cell

NO membrane-bound organelles. Smaller than eukaryotic cells. Nucleic region where DNA is kept.

Capsule

Sticky polysaccharide for attachment in pathogenic bacteria.

Pili

Extensions for attachment in pathogenic bacteria.

Flagella

Helps with motion. Composed of microtubules.

Nucleus

Nucleolus, Nuclear Envelope, Chromatin.

Nucleolus

Synthesizes ribosomal subunits and ribosomal RNA.

Nuclear Envelope

Separates the **nucleus** from the cytoplasm and provides a structural framework. Perforated by pores and continuous with the **endoplasmic reticulum.**

Endomembrane System.

ER, Vesicles, Lysosomes, Golgi apparatus, Plasma Membrane. Main role is to produce, fold, modify, sort and transport proteins to their destination.

Rough Endoplasmic Reticulum

Synthesis of secreted and membrane proteins. Network of sacs and tubes, ribosomes on its surface. 

Smooth Endoplasmic Reticulum

Synthesis of __**lipids**__. Storage of Ca2+. 

Detoxification of drugs and natural wastes (e.g in the liver). No ribosomes on its surface. 

Golgi apparatus

Factory in which proteins are processed, modified, and transported to their destinations.

Lysosomes

Rid cells of waste products; contain digestive enzymes.

Vacuole

*Storage of waste products and nutrients and hydrolysis of macromolecules.* 

Contractile vacuoles pump excess water out of the cell. 

*Central vacuole in plant cells; storage, protection, maintaining pressure within the cells.*  

Mitochondria

Cellular respiration occurs here. ATP is generated. 

Endosymbiont Theory

Chloroplasts

Responsible for photosynthesis. Endosymbiont Theory. Converts energy from sunlight into ATP.

Peroxisomes

Site of detoxification of oxygen radicals, O2- and alcohol. 

Catabolism of fatty acids. 

Different in origin from all other organelles. 

Organisms with a role in cell shape

Cell Wall, Microfilaments, Microtubules, Intermediate Filaments.

Microfilaments

7nm long tubes, also called actin filaments. Help with cell shape as microvilli, help with motility as pseudopods. Help with muscle contraction and cell division.

Intermediate Filaments

10 nm fibers. Support the cell, anchor organelles, form the nuclear lamina.

Microtubules

25 nm hollow fibers. Help with cell shape, cell movement (cilia and flagella). Help with cell division (mitotic spindle). Help with organelle movement, act as tracks for vesicles during protein secretion. Grow at centrioles and basal bodies.

Flagellum

Structure composed of microtubules resembling a whip. Helps with movement. Only present in sperm cells in humans.

Ribosomes

Complexes that make proteins.

Four types of proteins produced by the end-membrane system

Membrane, Lysosomal, Smooth ER, Secreted.

Overall Endomembrane System

Nuclear Envelope - Rough ER - Golgi apparatus - Transport Vesicles - Destination

Endosymbiont Theory

States that an early ancestor of eukaryotic cells engulfed a prokaryotic cell, which eventually formed a relationship with its host cell, becoming an **endosymbiont.** 

Over the course of evolution, the host cell and the endosymbiont merged into 1 organism. 

Assumed to be the origin of **mitochondria** and **chloroplasts.** 

Evidence for Endosymbiont Theory in Mitochondria + Chloroplasts

double membraned, individual DNA and ribosomes, semi-autonomous (grow + reproduce independent of cell).

Cell Junctions

Tight Junctions, Gap Junctions, Plasmodesmata, Desmosomes

Tight Junctions

Plasma membranes of close cells are tightly pressed against one another. 

Form continuous seals around cells, which prevents leakage of fluid across epithelial (skin) cells.

Gap Junctions

Embryos + Heart Tissues. Provide cytoplasmic channels. Consist of membrane proteins that create pores for substances to travel through.

Plasmodesmata

Channels that perforate cell walls and connect cells via the cytoplasm, sharing the same chemical environment. 

Unifies the plant. 

Desmosomes

Muscle cells. fastens cells together into strong sheets. Intermediate filaments anchor desmosomes in the cytoplasm.