Download File - SCIENTIST CINDY

General Biology MIDTEM II STUDY GUIDE
Page |1
General Biology Study Guide MIDTERM II
100 QUESTIONS 2 pts each.
Cell Structures and Function
Organic Chemistry
Membranes
Mitochondria and Chloroplasts
Digestion- Energy Processing – Cellular Respiration
______________________________________________________________
I.
ORGANELLES
BASICS
Cells are the Fundamental Units of Life
Organelles - Internal cellular structures that carry out specific functions in the cell (similar to our organs.
The word organelles mean “little organs” in Latin


Intracellular = “inside of the cell”
Extracellular = “outside of the cell”
Prokaryotic vs. Eukaryotic
Prokaryotic = DO NOT have a membrane-bound nucleus or organelles
Eukaryotic = DO have a membrane-bound nucleus or organelles
both plants and animal cells are eukaryotic
General Biology MIDTEM II STUDY GUIDE
Page |2
The 3 organelles in PLANTS ONLY are the
1) Cell Wall
a) The cell wall is made up of cellulose
This is FIBER (insoluble fiber = indigestible fiber)
Humans are unable to digest cellulose because the appropriate
enzymes to break it down.
b) Support, rigidity, and protection
c) Surrounds plasma membrane
2) Chloroplasts
a) Chloroplasts are where photosynthesis occurs in plant cells
i) Photosynthesis is the process by which plants convert water, carbon dioxide
and light energy (photos) into sugar and oxygen!
b) Chloroplasts are able to start the photosynthesis process, because it contains
photosensitive pigments, like chlorophyll.
i) Chlorophyll absorbs photons and undergoes a physical change in its
shape (a conformational change) which triggers a chemical reaction
c) Acquire energy through light (absorb photons!) and convert into chemical energy by
photosynthesis
General Biology MIDTEM II STUDY GUIDE
Page |3
3) Central vacuole
a) Large fluid filled structure –
i) Storage of water, wastes, and nutrients
ii) Influences cell size and shape
1) when water in vacuole of the plant cell is low, the plant will
become limp or wilt.
2) When there is a lot of water in the vacuole, the plant stands
up straight due to the TURGOR PRESSURE
HUMANS also have a
photosensitive pigment
(like chlorophyll)
In humans, we also have a photosensitive pigment (RHODOPSIN) in our retina that absorbs
photons (light energy) and kicks off the biological process that ends up as the sensory
perception of light. When rhodopsin absorbs a photon, the physical structure of the protein is
altered. This starts a cascade of events that lead to sight.
General Biology MIDTEM II STUDY GUIDE
ANIMAL CELL
Nucleus and
Nucleolus
The nucleus holds all the genetic material and
instructions for our body in its deoxyribonucleic
acid (DNA). The nucleolus also exists inside the
nucleus and is where ribosomes are made. After
the ribosomes are made in the nucleolus, they
leave the nucleus (through the nuclear
membrane aka nuclear envelope) and will dock
onto the nearby endoplasmic reticulum. This area
of the endoplasmic reticulum is called the ROUGH
Page |4
General Biology MIDTEM II STUDY GUIDE
Page |5
ENDOPLASMIC RETICULUM because it appears “bumpy” or “rough” due to the presence of
ribosomes. Ribosome are the sight of protein synthesis.
Cell Membrane (aka Plasma Membrane)
Cell membranes are made up
of phospholipids. Phospholipids are
called amphiphilic, because they
have a hydrophilic (waterloving) head and hydrophobic (waterfearing) tails. The head consists of a
negatively charges phosphate ion
(PO4-) and 2 fatty acid tails.
When phospholipids are placed in
water, they spontaneously form a
lipid bilayer. In this bilayer the fatty
acid hydrophobic tails will orient
themselves to face one another with the
polar phosphate heads facing outward. It is
this structure that makes up the
membranes of our cells.
The function of the membrane is to regulate what comes into the cell and what goes out of
the cell. It is for this reason that the concept of osmosis is key for understanding how the
cell depends on the microenvironment by which it is surrounded.
Membrane are made up of a double lipid bilayer (2 layers) of phospholipids. (see above).
General Biology MIDTEM II STUDY GUIDE
Page |6
Cytoplasm
Cytoplasm (aka intracellular fluid) – this is the liquid substance inside the plasma
membrane and outside the nucleus.
Cilia and Smokers Cough
The airways are lined with cilia: tiny hair-like cells that catch toxins in inhaled air and move
them upwards toward the mouth and sweep harmful substances out of the lungs.
Smoking paralyzes these cells so they’re unable to do their job. Instead of being caught in transit,
toxins are allowed
to enter the lungs,
where they settle
and create
inflammation.
Cilia that are
damaged or
destroyed can no
longer sweep
harmful
substances, such as
dust, bacteria, and
viruses out of the
lung. This leads to
a build-up of
mucus mixed with
these substances in
the respiratory
tract, which the
body tires to clear
by coughing.
During the night,
these cilia begin to
repair themselves
as they’re no
longer exposed to
the toxins in
smoke. As the cilia
General Biology MIDTEM II STUDY GUIDE
Page |7
are called upon to catch and remove the accumulated toxins, the result is an increase in coughing
upon arising in the morning.
Endoplasmic reticulum
Endoplasmic reticulum (cell
circulatory system? / highway?)
There are two types of
endoplasmic reticulum: rough
and smooth.
 The rough endoplasmic
reticulum is bumpy due to
the presence of
ribosomes. Remember
that ribosomes are the
sites of protein synthesis.
 The smooth endoplasmic
reticulum does NOT
contain ribosomes, so it
appears smooth. The
smooth endoplasmic
reticulum (ER) functions to build and break down lipids (fats).
Ribosomes
Ribosomes are the site of protein synthesis. Ribosomes link amino acids together according to
the direction it received from the messenger RNA (mRNA) molecules.
Golgi Body (cell post office)
The Golgi Body (aka Golgi apparatus or Golgi complex) – After proteins are made on the
ribosome, they are shipped to the Golgi Body. In the Golgi Body, the proteins are packaged,
modified and shipped out. The Golgi Body will add an amino acid signaling sequence on the end
of the protein as a little “address tag”. This signal sequence instructs the cell on where the
protein needs to go. They can travel into the nucleus, stay in the cytoplasm, travel to one of the
organelles, become imbedded in the cell membrane, or even exit the cell altogether.
Lysosomes
General Biology MIDTEM II STUDY GUIDE
Page |8
Lysosomes – (cell digestive tract?) - Contain enzymes for intracellular digestion of bacteria,
cellular debris, and worn out cell parts
The endosymbiosis theory




The endosymbiosis theory explains the origins of organelles such as mitochondria and
chloroplasts in eukaryotic cells.
According to endosymbiosis theory, one prokaryotic cell probably engulfed another,
smaller prokaryotic cell (a bacterium) with the intention of eating it! However, for some
unknown reason, the bacterium did not get digested. Instead, they lived happily ever
after.
The bacterium flourished within the cell, because the host cell provided food and
shelter.
In return the bacterium developed into mitochondria (in animal cells) and chloroplasts
(in plant cells)
What evidence do we have of the endosymbiotic theory with regard to mitochondria?


The mitochondria reproduce independently using binary fission (asexually) and have
their own bacterial plasmid which is a circular strand of DNA.
All of your mitochondria came from your mother (mitochondria are maternally
inherited). Since mitochondria reproduce by making clones, that means that your
mitochondrial DNA is identical to your mother, and your mother’s mother, and your
mother’s mother’s mother and so on!
General Biology MIDTEM II STUDY GUIDE

Page |9
Mitochondria reproduce independently inside the cell depending on the energy demand
of the cell. They can increase their numbers when the energy demand on the cell is high
(for example, when a muscle cell is being used a lot) or decrease their numbers when
the muscle cell is not being used very much or very often.
Mitochondria
The mitochondria is like the cell engine – functions to release
of energy from sugars in the form of ATP through cellular
respiration. Has a double double lipid bilayer. This is a remnant
from when the first mitochondrion was engulfed by a host cell
(see endosymbiotic theory). SEE MORE IN CELLULAR
RESPIRATION.
_____________________________________________________________________________
II) Organic Chemistry
The Basics - CARBON IS KEY
One atom of carbon can combine with up to four
other atoms. Therefore, organic compounds
usually are large and can have several atoms and
molecules bonded together. The 4 important
organic molecules include carbohydrates, proteins,
nucleic acids, and lipids.
Carbon atoms have four electrons that can bond
with other atoms. A bond is made up of 2 electrons
(1 electron from each atom participating in the
bond.) Carbons can form long chains and circular
molecules and branching. It is willing to react with
just about anything!
CHEMICAL EVOLUTION
The first organic molecules were small carbon-based molecules made up of only a few atoms. All
living things consist of organic molecules, centered around the element carbon. Organic
molecules evolved before cells, perhaps as long as 4 billion years ago. Complex molecules can be
formed by bonding many carbon atoms together in a straight line or by connecting carbons
General Biology MIDTEM II STUDY GUIDE
P a g e | 10
together to form rings. Recall that C H O N = 96% of living things. But, how did these carbonbased molecules necessary for life first form?
Scientists believe that the first organic molecules formed about 4 billion years ago. It is thought
that lightening sparked chemical reactions in Earth’s early atmosphere. Some studies have
speculated that lightning activity played a crucial role in the development of not only Earth's early
atmosphere, but also early life. Scientists hypothesize that this created a “soup” of organic
molecules from inorganic chemicals.
In 1953, scientists Stanley Miller and Harold Urey used their imaginations to test this
hypothesis. They used a mixture of gases to represent Earth’s early atmosphere. Then, they
passed sparks through the gases to represent lightning. Within a week, several simple organic
molecules had formed.
RNA World Hypothesis
RNA may have been the first organic molecule to form as well as the basis of early life. The first
cells consisted of little more than an organic molecule such as RNA inside a lipid membrane. In
the lab, when we recreate the conditions of Early Earth, RNA behaves like DNA! There was even
an electron transfer function which would be enough to evolve into a molecule used for
photosynthesis!
Saccharides (SUGARS)
Monosaccharides are the simplest form of carbohydrates with only one simple sugar. This are
considered ‘simple sugars’. Examples of monosaccharides are glucose, fructose, and galactose.
Disaccharides are formed when two monosaccharides, or two single simple sugars, form a
bond. Examples of disaccharides include sucrose, maltose, and lactose.
Polysaccharides are made up of “MANY” monosaccharides bound together. These are
considered ‘complex carbohydrates’. Examples are starch, cellulose, and glycogen. They are
generally large and often have a complex branched connectivity.
The suffix (-ose = means SUGAR).
General Biology MIDTEM II STUDY GUIDE
P a g e | 11
Lipids FATS
There are three major groups of
lipids:
1) Triglycerides - fats, oils, and
waxes. Triglycerides consist of
three fatty acids bonded to a
glycerol molecule.
2) Phospholipids – makes up cell membranes. Will spontaneously form a membrane in water in
the lab!
3) Steroids – hormones
Triglycerides
General Biology MIDTEM II STUDY GUIDE
P a g e | 12
Triglycerides consist of three fatty acids bonded to a glycerol molecule.
A saturated fatty acid has the maximum possible number of hydrogens bonded to it. The
carbon back bone contains only single bonds.
Unsaturated fatty acids have less hydrogen bonded to it due to having one or more double
bonds. This double bond is a the CIS configuration.
“Transfats” are unsaturated fats that have one or more double bonds in a TRANS
configuration. [CIS (same) vs TRANS (opposite)] CIS fats are healthy fats that promote good
cholesterol. TRANS fats, on the other hand, can be harmful and can contribute to a decrease in
cardiovascular health. In November 2013, the U.S. Food and Drug Administration (FDA) put
forth a mandate that food companies eliminate TRANS fats from their products over time.
Phospholipids
General Biology MIDTEM II STUDY GUIDE
P a g e | 13
Cell membranes are made up
of phospholipids. Phospholipids are
called amphiphilic, because they
have a hydrophilic (waterloving) head and hydrophobic (waterfearing) tails. The head consists of a
negatively charges phosphate ion
(PO4-) and 2 fatty acid tails.
Phospholipids are structurally similar
to fats, except that they contain only
two fatty acids attached to glycerol
instead of three. they consist of a
hydrophillic (polar) head and 2
hydrophobic (non-polar) tails.
Steroids
An example of steroids are hormones like estrogen
and testosterone.
PROTEINS
Nearly every dynamic function in your body
depends on proteins. A protein is a polymer of
small building blocks called amino acids held
together by peptide bonds. They are the most
structurally and functionally varied molecules.
Proteins perform a vast array of functions within organisms, including catalyzing metabolic
reactions, DNA replication, responding to stimuli, and transporting molecules from one location
to another.
General Biology MIDTEM II STUDY GUIDE
P a g e | 14
Nucleic Acids
DNA and RNA are built from single units (monomers) of nucleic acids.
DNA = Deoxyribonucleic acid
RNA = Ribonucleic acid
DIGESTION AND CELULAR RESPIRATION
Molecule Type
Carbohydrates
Fats
Proteins
Where Digested
mouth, small intestine
small intestine
stomach, small intestine
Broken Down Into
monosaccharides e.g. glucose
glycerol & fatty acids
amino acids
_____________________________________________________________
THE BASICS - Cellular respiration is this process in which oxygen and glucose are used to create ATP,
carbon dioxide, and water. ATP, carbon dioxide, and water are all products of this process because they are
what is created. Carbon dioxide is released as a gas when you exhale. Water is a liquid that is excreted
through urine, sweat, and vapor in breath. Lastly, ATP is used to store energy for the body.
Cellular respiration is the process in which the food you eat is broken down to release energy in the form of
ATP. ATP, or adenosine triphosphate, is a molecule that delivers energy around your body so your cells can
perform the functions they need to sustain life. The food your body breaks down during cellular respiration is
called glucose, which is a sugar.
Glucose is the ONLY molecule the brain can use as energy. It is also the preferred form of
energy for nearly all of the activities of the cell!
Sugars (carbohydrates) (saccharides) are the ONLY molecules that begin to be chemically
digested in your mouth! Your saliva contains the enzyme amylase (the suffix ‘-ase’ means
enzyme) which acts to catalyze (make the reaction go faster) the breakdown of starch into
sugar. Starch is a polysaccharide made up of many glucose monomers. Starch gets digested
(broken down) by the amylase enzyme, into maltose which is a disaccharide made up of only 2
glucose monomers.
General Biology MIDTEM II STUDY GUIDE
P a g e | 15
To create ATP, your body takes in glucose from food and oxygen from the air you breathe. Your body then
converts those two things into water, ATP, and carbon dioxide, which are products of cellular respiration.
This chemical equation shows the reactants for cellular respiration on the left, before the arrow.
The products are created during cellular respiration and are shown on the right, after the arrow. The arrow
represents molecules being rearranged and shows that change is occurring.
AMYLASE is an enzyme that is found in our bodies that functions to help the body in
the digestion food. Amylase is found in saliva and in the pancreas. Amylase catalyzes
the hydrolysis (breaking down) of starch, glycogen and related polysaccharides into
more simple and readily usable forms of sugar.
Some organisms eat plants. Some organisms eat animals. Some organisms even make their own food, like in
the case of plants and some bacteria. However, what we all do with that food is the same.
General Biology MIDTEM II STUDY GUIDE
P a g e | 16
Structure and Function of ATP
Food contains important chemicals called organic compounds. These chemical compounds have energy
stored in their bonds that your body wants and needs, so your body needs to extract that energy and turn it into
a usable form. That usable form is the molecule ATP, or adenosine triphosphate. ATP is the form of energy
used by all living things.
The easiest way to think about ATP is like a rechargeable battery. When ATP is charged and energized, it has
3 phosphates. But in order for your body to use ATP energy, it must break the bond between the last two
phosphates. Breaking that bond releases the energy your body needs for survival. However, this chemical
reaction also changes ATP into ADP (adenosine diphosphate). ADP is like a rechargeable battery that has lost
its charge. To recharge ADP, your body must convert food to energy through this process of cellular
respiration.
Cellular respiration
This reaction takes place over the course of three major reaction pathways



Glycolysis – uses 2 ATP
The Krebs Cycle – creates 4 ATP
Electron Transport Phosphorylation (chemiosmosis) – 32 ATP
The Krebs cycle and the electron transport phosphorylation happens in the mitochondria -
General Biology MIDTEM II STUDY GUIDE
P a g e | 17
Mitochondria are rod shaped structure found in both animal and plant cells. It is a double
membrane bound organelle. It has the outer membrane and the inner membrane. The
membranes
are
made
up
of
phospholipids
and
proteins.
The components of mitochondria are as
follows:
Outer membrane

It is smooth and is composed of equal
amounts of phospholipids and proteins.
 It has a large number of special
proteins known as the porins.
 The porins are integral membrane
proteins and they allow the movement
of molecules that are of 5000 daltons or
less in weight to pass through it.
 The outer membrane is freely
permeable to nutrient molecules, ions,
energy molecules like the ATP and ADP
molecules.
Inner membrane






The inner membrane of mitochondria is more complex in structure.
It is folded into a number of folds many times and is known as the cristae.
This folding help to increase the surface ares inside the organelle.
The cristae and the proteins of the inner membrane aids in the production of ATP
molecules.
Various chemical reactions takes place in the inner membrane of the mitochondria.
Unlike the outer membrane, the inner membrane is strictly permeable, it is permeable
only to oxygen, ATP and it also helps in regulating transfer of metabolites across the
membrane.
Matrix

The matrix of the mitochondria is a complex mixture of proteins and enzymes. These
enzymes are important for the synthesis of ATP molecules, mitochondrial ribosomes,
tRNAs and mitochondrial DNA.
Functions of mitochondria depends on the cell type in which they are present.
General Biology MIDTEM II STUDY GUIDE

P a g e | 18
The most important function of the mitochondria is to produce energy. The simpler
molecules of nutrition are sent to the mitochondria to be processed and to produce
charged molecules. These charged molecules combine with oxygen and produce ATP
molecules. This process is known as oxidative phosphorylation.