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Title: Biological Diversity Evolution
Description: Wilfrid Laurier University Year One Biology notes summary of textbook information with emphasis on important topics
Description: Wilfrid Laurier University Year One Biology notes summary of textbook information with emphasis on important topics
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Biology Midterm 1 Review
Phospholipids
• Amphipathic (having both hydrophilic and hydrophobic parts)
• Polar head à hydrophilic
• 2 Non-‐polar hydrocarbon tails à hydrophobic
Module 13: Cells
• Cells compose organisms or can be organisms
o Unicellular organisms consist of a single cell
o Multicellular organisms can have specialized cells for different functions but cells
have same basic structure
• Cell Theory
o 1
...
Cells are the basic structural and functional unit of life
o 3
...
• Large cells are less capable of transporting materials across plasma membrane
• The volume of a cell determines the bio-‐chemical capacity of that cell
• Increase radius by 2x, increases surface area by 4x, increases volume by 8x
• Exceptions to the rule: egg cells mostly metabolically inactive, need few nutrients and
produce little waste
...
• Most bacterial cells range from about
1 to 10 microns long
...
• Resolution and magnification
maximizes are ability to see cells
clearly
...
• Cells separate the internal environment from the external environment in order to
maintain homeostasis
...
• The Plasma Membrane is a phospholipid bilayer that contains proteins and other
components such as the lipid cholesterol
...
• Cells must be able to build proteins, achieved by ribosomes
...
• The medium for chemical process is the semifluid matrix of the cell, called the cytosol
...
(process called
conjugation)
• Through the pilus, plasmids are copied and transferred to neighboring cells
Cell fractionalization seperates a cell’s components
• Cell fractionalization is a laboratory technique used for isolating cell organelles and
other cell components for study
...
•
Bacterial cells are mainly made of
peptidoglycans, molecules formed from
carbohydrates linked by peptides
...
• Flagella; long mobile projections used in moving the cell from one place to another
• Cilia; Shorter projections
• Fimbriae; short projections that help prokaryotic cells attach to surfaces
...
Parasiting
The endosymbiotic Theory
• Attempts to explain how eukaryotic cells evolved from prokaryotic ones
...
The engulfed prokaryote was not digested and developed a symbiotic, or mutually
beneficial, relationship in which it provided nutrition to its host, while the host
protected it from the environment
...
• 2nd endosymbiotic event is believe to have given rise to chloroplasts
...
o Mitochondria and chloroplasts have DNA that is distinct from the nuclear DNA
and that is circular like bacterial DNA
...
Module 14: Eukaryotic Cells
• The compartments in eukaryotic cells are called organelles: membrane-‐bound structure
enclosed by semi-‐permeable phospholipid membrane that is very similar in composition
to the plasma membrane
...
• One or more linear chromosomes are contained within a double membrane-‐bound
organelle called the nucleus
Why is the Nucleus Important?
• Nucleus functions much like the brain of the cell
• Eukaryotic cell nucleus is often larger than an entire prokaryote
• Nucleus contains cell chromosomes which consists of DNA and associated proteins
• Surrounded by a double membrane called the nuclear envelope, made of two
phospholipid bilayers
...
o Ribosomal RNA (rRNA) is synthesized in the nucleolus and combined with
proteins to form the small and large subunits of the ribosomes
§ Ribosomes are the protein producing factories of the cell
...
More on Ribosomes
• Unifying feature of all cell types
o Bacterial, archaeal, and eukaryotic are all slightly different
• In Eukaryotes, some are free in cytosol, others are attached to endoplasmic reticulum
membranes
o Still others are found in mitochondria and chlorplasts
• Though ribosomes are made in the nucleolus, protein synthesis occurs in the cytoplasm
or the Rough Endoplasmic Reticulum (in cytosol, outside of nucleus)
• DNA never leaves the nucleus, instead, a transcript of one or more genes is made in the
form of mRNA, carries transcription outside of the molecule to the ribosomes
• If mRNA encodes a soluble cytosolic protein, the ribosome remains free in the
cytoplasm
• If mRNA encodes a membrane-‐embedded or secretory protein, the ribosome attaches
itself to the Rough Endoplasmic Reticulum
...
o Nuclear Envelope
o ER
o Golgi Complex
o Lysosomes/Vacuoles
o Vesicles
o Plasma Membrane
• Golgi complex/apparatus
o “shipping and receiving” center of the cell’s endomembrane system
o Composed of a stack of separate, flattened membrane sacs
...
Then fuse
with plasma membrane or membrane of other organelles
§ Vacuoles: vesicles used for storage, transportation, and specialized
functions
...
§ Lysosomes: vesicles containing powerful enzymes that digest food items
engulfed by the cell
...
§ The vesicle containing
the engulfed food item is
called a food vacuole
§ Lysosomes fuse with the
food vacuoles and their
digestive enzymes break
down the food items
...
o Lysosomes also use digestive enzymes to
recycle cellular components by Autophagy
...
Exocytosis and Endocytosis
• Exocytosis: secretory vesicle releases the vesicle
content to the cell exterior, fuses with plasma
membrane
• Endocytosis: Materials from the cell exterior are
enclosed in a segment of the plasma membrane,
pinches off an as endocytic vesicle
...
• They also contain their own DNA and ribosomes capable of synthesizing their
own proteins
• They can divide and multiply largely free of the constraints of cell division
...
The
engulfed prokaryotes became
symbiotic, benefitting from living
safely within the host cells cytoplasm
and gaining nutrients
...
This
symbiotic relationship ultimately
evolved to a point where the two
cells were no longer independent
...
• The inner membrane surrounds the
interior of the mitochondrion, called the
matrix
...
• An electrochemical gradient formed
across the inner membrane provides
energy for ATP synthesis
...
o The fluid surrounding the thylakoid is called the stroma
...
• Contain enzymes that break down toxic molecules by removing hydrogen via a set of
oxidation reactions
...
• Peroxisomes must immediately convert excess hydrogen peroxide into water
...
o Great example of the compartmentalization of harmful materials and volatile
chemical reactions within a membrane-‐bound organelle
...
o Building blocks: individuals lipids, small carbohydrates, amino acids
o Conditions were very different, earth was hot, lacked oxygen, highly reducing
environment (reducing are good conditions for promoting new chemical bonds)
§ You didn’t need organisms to produce these building blocks
• Reducing atmosphere that lacked oxygen
o H2S, CO2, NH3, CH4, H2O (vapour)
• Allows for synthesis of complex organic molecules
• On abiotical Earth, polymerization of organic macromolecule may have formed on clay
surfaces
Miller-‐Urey Experiment
• Simulated Earth’s early conditions
and created several organic
molecules including amino acids
...
• Most recent evidence suggests that
the early atmosphere was mostly
nitrogen and carbon dioxide, making
it closer to neutral: neither electron-‐
adding nor electron-‐removing
...
The
dissolved material precipitates out, often causing whats known as a “black
smoker”
o Archaebacteria in black smokers obtain their energy from hydrogen sulfide and
replicate
...
o Their presence in hydrothermal vents constitutes one piece of evidence
supporting the idea that life evolved there
...
2 BYA
o Hydrogen sulfide
and methane
o Hydrothermal vents in the deep sea provide an environment favourable to the
development of organic molecules
...
How were the first molecules made if there were no
enzymes?
• Was RNA the first genetic material?
o Some types of RNA catalyze reactions, like enzymes
...
o Ribozymes also produce nucleotide sequences that directly complement a piece
of RNA, and some ribozymes replicate themselves
...
o How could a cell replicate without proteins or enzymes?
o How could cell membranes have developed?
§ Adding lipids or other organic molecules to water results in the creation
of vesicles or fluid-‐filled sacs
...
§ The organic molecules cluster
on the surface of the clay
...
§ Nucleic polymerization is catalyzed by clay particles
...
o Polymerization reactions may have occurred on solid surfaces
§ Solid surfaces are good for catalyzing chemical reactions
§ Promotes polymerization of organic molecules
• E
...
clay
Processes that influence the origin of species are not the same as those that influence the
origin of life
...
Forms of life display order
o E
...
a protein (longer) has more order than an amino acid, linked together in a
particular order
2
...
Reproduce
4
...
Exhibit homeostasis
o Internal balance, equilibrium
6
...
Evolve
Is a Virus Alive?
• Display order, contain nucleic acids
• Reproduce
• Evolve
o Genomes are frequently changing, that is why it is hard to get rid of
• No cell structure
History of Earth
• 4
...
9 BYA (chemical), 3
...
1-‐2
...
6
million years
Biologically Important Macromolecules
• 4 major types of macromolecules important for
all forms of life
o nucleic acid (DNA & RNA)
o proteins
o lipids
o carbohydrates
o all except lipids are polymers made up
from simpler building blocks, all are
made within cells by complex metabolic
pathways
...
5-‐3
...
5 BYA
o The increase in O2 led to the evolution of aerobic respiration (prokaryotes)
• Unicellular eukaryotes evolved ~2
...
2-‐1
...
g
Title: Biological Diversity Evolution
Description: Wilfrid Laurier University Year One Biology notes summary of textbook information with emphasis on important topics
Description: Wilfrid Laurier University Year One Biology notes summary of textbook information with emphasis on important topics