BIOLOGY
MIDTERM EXAM
REVIEW
The Science of Life
Biology is the science of LIFE.
Life:
• Organisms are made from and develop
from cells!
–
–
Unicellular
Multicellular
•
Cells of multicellular organisms undergo
differentiation.
The Science of Life
Cell differentiation is a process in which a generic cell develops
into a specific type of cell in response to specific triggers from
the body or the cell itself.
The Science of Life
Biology is the science of LIFE.
Life:
• All living things maintain stable
internal conditions know as homeostasis!
• All organisms reproduce – they
pass down their genetic
information to offspring
through DNA.
–
–
Sexual reproduction
Asexual reproduction
The Science of Life
Asexual reproduction
1. Binary Fission (prokaryotes)
2. Mitosis (eukaryotes)
•
Results in identical cells, or
clones of the parents!!
Sexual reproduction
1. Meiosis (eukaryotes)
– Results in gametes - sex cells (sperm and egg)
– Cuts chromosomes in half
– Adds genetic variety!!
The Science of Life
Biology is the science of LIFE.
Life:
• Populations of organisms evolve or
change over time.
• All organisms interact with their living
and non-living environment.
•
Ecology – branch of biology that studies
these interactions.
The Science of Life
Biology is the science of LIFE.
Life:
• All living things must obtain energy.
•
•
Heterotrophs
Autotrophs
Photosynthesis and Cellular Respiration
The Science of Life
SCIENTIFIC METHOD:
How Scientists solve a problem or answer
a question…
The Science of Life
The Science of Life
Measurement
Chemistry
• Everything in the universe is made
of matter.
• Everything in the universe has mass.
Chemistry
Elements are pure substances that can
not be broken down into simpler kinds
of matter
Chemistry
An Atom is the simplest particle of an
element.
Chemistry
Atoms are held together by bonds
Covalent Bonds
Ionic Bonds
Chemistry
Energy & Matter
States of Matter:
Chemistry
Chemical Reactions:
Energy is
released
Energy is
absorbed
Chemistry
Solutions:
Chemistry
Acid: 0 - 6.5
Acids and Bases
Neutral – 7.0
Base: 7.5 - 14
Chemistry
Properties of Water
Capillarity
BIOCHEMISTRY
The Building Blocks of Life:
Four types of macromolecules
(large, carbon-based organic molecules)
are found in living organisms.
The Element of Life
BIOCHEMISTRY
The Building Blocks of Life:
The Molecules of Life:
Most are polymers—chains of smaller
molecules (monomers) that form through
dehydration synthesis.
(the loss or removal of a water molecule).
BIOCHEMISTRY
Carbohydrates:
• Energy-storing molecules containing carbon,
hydrogen, and oxygen in a 1:2:1 ratio.
• Monosaccharides, such as glucose (C6H12O6),
are single-sugar subunits (monomers) often
found as rings.
• Disaccharides have two monosaccharide
subunits
• Polysaccharides, such as starch (plant
storage), glycogen (animal storage), and
cellulose (plant fiber), are long chains of sugars.
BIOCHEMISTRY
Lipids:
Hydrocarbon-based molecules that are
hydrophobic (insoluble in water or water ‘hating’).
There are three main families of lipids:
Fats, Oils & Waxes, Steroids and
Phospholipids
BIOCHEMISTRY
FATS & OILS:
• Large, HIGH energy-storing molecules, each
built from two components:
– One molecule of glycerol, a three-carbon alcohol.
– Three fatty acids, long hydrocarbon chains that
attach to the glycerol backbone.
• (Hence, fats are also called triglycerides.)
BIOCHEMISTRY
Steroids: Four fused-hydrocarbon rings, such
as cholesterol.
Phospholipids: Glycerol with two fatty acids and
a phosphate group attached (found in cell
membranes).
BIOCHEMISTRY
PROTIENS
Long polymer chains called polypeptides built
from single amino acids linked together by
peptide bonds.
BIOCHEMISTRY
PROTIENS
Every amino acid contains a central carbon with
an amino group (NH2), a carboxyl group (COOH),
hydrogen (H), and one of 20 side groups (R) that
makes each amino acid different.
BIOCHEMISTRY
ENZYMES:
Enzymes are proteins
capable of speeding
chemical reactions without being consumed (used).
Enzymes lower the amount of energy needed to
start a reaction.
The substrate binds to the enzyme’s active site in an
induced fit, in which the enzyme changes its shape
to wrap itself around the substrate.
BIOCHEMISTRY
ENZYMES:
Enzymes have a variety of functions in the
body, including:
• digesting food
• Transmitting nerve impulses
• making our muscles work.
BIOCHEMISTRY
NUCLEIC ACIDS:
Polymers of nucleotides that encode genetic
information.
There are two forms:
deoxyribonucleic acid (DNA) and ribonucleic
acid (RNA).
BIOCHEMISTRY
NUCLEIC ACIDS:
Individual nucleotides are linked by phosphate
bonds and contain
three basic parts:
*Phosphate group, *5 carbon sugar (deoxyribose
or ribose) and a nitrogenous base.
BIOCHEMISTRY
NUCLEIC ACIDS:
The double helix (double strand) is formed from weak
hydrogen bonds between complementary nitrogenous
bases (adenine and thymine; guanine and cytosine) on
opposite strands of a the DNA molecule.
BIOCHEMISTRY
NUCLEIC ACIDS:
Complementary
Base Pairing:
In DNA,
nitrogenous
base Adenine
always pairs
with Thymine;
Cytosine always
pairs with
Guanine
BIOCHEMISTRY
Structure & Function
of the Cell
THE CELL THEORY
1. Every living organism is made up
of cells
2. Cells are the lowest level of
structure capable of performing all
the activities of life.
3. All cells arise from
preexisting cells.
Structure & Function
of the Cell
• Not all cells are alike
• Cells are limited in size by the
ration between their surface area and
volume
• A cells
shape
determines
its function
TYPES OF CELLS
Prokaryotic Cells – simple cell, no membrane bound
nucleus (only nucleoid region with DNA) or no
membrane bound organelles (i.e no mitochondria,
golgi body, etc. but have ribosomes)
Eukaryotic Cells – more complex cell, membrane
bound nucleus (DNA containing) and organelles.
Animal Cell & Plant Cell (Eukaryotic)
Bacteria Cell (Prokaryotic)
TYPES OF CELLS
CELL MEMBRANE
Cell membrane:
Serves as an external barrier and encloses
organelles.
The basic unit of the cell membrane is the
phospholipid bi-layer molecule
Cell membranes are semipermeable, allowing
passage of gases (O2 & CO2), lipids, and small
polar molecules but not charged molecules (ions
and proteins) or large polar molecules without
the use of ENERGY (ATP).
CELL MEMBRANE
Membrane proteins embedded in the bilayer help
transport molecules unable to cross the
membrane independently
TYPES OF CELLS
Cells of Eukaryotes:
Eukaryotes include multicellular plants
and animals, fungi and some unicellular
protists.
Their cells contain membrane-bound
organelles, each of which performs
specific functions.
TYPES OF CELLS
Nucleus: Membrane-bound storage site
of genetic information that determines
heredity and directs the activities of a
cell.
Mitochondria: Membrane bound Power
plant of the cell and the location of
aerobic respiration.
TYPES OF CELLS
Smooth/rough endoplasmic reticulum
(SER/RER): Network of membranes
where lipids and proteins are
synthesized.
Rough ER is covered with ribosomes.
Golgi apparatus: Organelle that packages
and exports proteins and lipids produced
in the ER.
TYPES OF CELLS
Vesicles: Sacs in which substances are
transported or stored.
Lysosomes: Vesicles of digestive enzymes that
degrade old cellular components.
TYPES OF CELLS
Plant cells contain several
additional components:
Chloroplasts: Sites of
photosynthesis. Contain
chlorophyll (a green pigment)
and have a double membrane.
Vacuole: Vesicle used to store
water, proteins, and wastes.
Cell wall: Rigid cellulose layer
around the cell membrane.
ORGANELLES
TYPES OF CELLS
Cells of Prokaryotes:
Prokaryotes include the simplest unicellular
organisms and were the earliest cells to evolve
(bacteria).
**Major differences from eukaryotes**
– Genetic material (DNA) floats in the
cytoplasm in a concentrated but unbounded
region called the nucleoid.
– There are no membrane-bound organelles.
TYPES OF CELLS
CELL REPRODUCTION
DNA is the cell’s genetic material;
chromosomes are the carriers of
this genetic information.
In prokaryotes, the chromosome
is a single circle of DNA.
In eukaryotes, each chromosome
is a complex of DNA and proteins
found in the nucleus.
CELL REPRODUCTION
Prokaryotic cells reproduce via binary
fission (asexual). In this process, DNA is
replicated, and the cell splits in two roughly
equal parts, each with a copy of the cell’s
DNA.
Eukaryotic cells reproduce sexually via the
creation of two identical diploid cells from
one diploid cell. Diploid (2N) refers to the
total number of chromosomes in autosomal
cells.
HOMESTASIS & TRANSPORT
Diffusion & Passive
Transport
(Require No Energy):
Molecules move freely across a
membrane to balance a
concentration gradient, from
areas of high to low
concentration.
Diffusion of water is called
osmosis.
HOMESTASIS & TRANSPORT
Osmosis is the diffusion of
water across a membrane. Like
other molecules, water will
move from an area of high
concentration to an area of low
concentration (depends on the
environment surrounding cell).
•Hypertonic - Solution that has a
Water
Water
Water
higher concentration of solute and
a lower concentration of water
than the cell.
•Hypotonic - Solution that has a
lower concentration of solute and
a higher concentration of water
than the cell.
HOMESTASIS & TRANSPORT
Diffusion & Passive
Transport
(Require No Energy):
Facilitated diffusion:
Molecules cross an
impermeable or semipermeable
membrane down their
concentration gradient but
must do so via
special channels.
HOMESTASIS & TRANSPORT
Active transport (Require Energy)
Transport of molecules from areas of low to high
concentrations across a membrane using an
ATP Energy-dependent transport protein.
• Endocytosis: Enveloping of an exterior substance
within a membranous vesicle for admission to the cell
interior.
– Pinocytosis: Endocytosis of dissolved liquid molecules.
– Phagocytosis: Endocytosis of undissolved solid matter.
• Exocytosis: Extrusion of material from a cell by
discharge from vesicles at the cell surface.
HOMESTASIS & TRANSPORT
.
CLASSIFICATION
To study so many life-forms, biologists have
organized them into numerous groups based
on their similar characteristics.
Classifying and naming organisms is key to
distinguishing, describing and understanding
the relationships between living and non-living
(extinct) organisms.
The branch of biology that deals with
classification of life-forms is known as
taxonomy.
CLASSIFICATION
In response to the need for better organization, an
18th century Swedish botanist named Carolus
Linnaeus offered a solution to the confusion of
classifying and naming organisms.
Linnaeus’s classified animals based on their
similarities in morphology (form & structure), rather
than by location.
(i.e. bats have wings but are not birds)
CLASSIFICATION
Carolus Linnaeus’s Classification System:
There are two important features of this
system:
1. The system classifies species into
hierarchical levels, in which level is nested
within larger levels (taxa).
2. Each species has a two-part name.
CLASSIFICATION
Part 1 - Seven Levels (taxa) of Classification
Keep Plates Clean Or Family Gets Sick!
Kingdom
Phylum
Class
Order
Family
Genus
Species
CLASSIFICATION
CLASSIFICATION
Part 2 - Binominal Nomenclature
The two-part name Linnaeus gave each organism is a
Latin, scientific name.
Genus, species = Panthera leo
CLASSIFICATION
Biologists have developed a precise method to
help them classify and identify unknown
organisms.
The classification tool called a dichotomous
key, uses a logical approach to classify an
organism.
CLASSIFICATION
The Six Kingdom System:
CLASSIFICATION
CLASSIFICATION
The New Three Domain System
THE CONTROLLED
EXPERIMENT
Most experiments in Biology are
controlled experiments - Used to gather
under controlled conditions.
data
– performed to test your hypothesis(an
educated guess) (prove or disprove it)
– Based on a comparison of a control group
with an experimental group.
THE CONTROLLED
EXPERIMENT
All factors in the control group and the
experimental group are identical except for
one:
• independent variable - what is being tested
During the experiment, observations and
measurements are taken from both groups,
looking specifically at another factor or
variable:
• dependent variable - dependent because it is
driven by/or results from the independent
variable.