Biology Final: Semester 1 Flashcards
Know the 9 most common elements in living systems (SPONCHNa CaFé) and know a function/ role for each
Sulfer: Formation of some amino acids
Phosphorus: Formation of phospholipids/ nucleotides/ ATP/ nucleic acids
Sodium: Membrane function, osmoregulation, sending nerve impulses
Calcium: Enzyme co-factor, cellular messenger, formation of bones/ teeth, nerve transmission, muscle contraction Iron: In cytochromes and hemoglobin
Carbon: forms the foundation of ALL four classes of organic compounds, can form 4 covalent bonds
Hydrogen: structural component of ALL four classes of organic compounds; reducing agent in photosynthesis and cellular respiration
Oxygen: used in aerobic respiration in cells
Nitrogen: formation of amino acids, nucleotides, and ATP
Know the four most common elements in living systems (CHON) and a function/ role for each
Carbon – forms the foundation of ALL four classes of organic compounds, can form 4 covalent bonds
Hydrogen – structural component of ALL four classes of organic compounds; reducing agent in photosynthesis and cellular respiration
Oxygen – used in aerobic respiration in cells (to make ATP = Adenosine Triphosphate, the cell’s “energy” molecule)
Nitrogen – formation of amino acids (which make up proteins), nucleotides (which make up nucleic acids (DNA/ RNA)), and ATP
+++Explain and diagram the structure of water molecules (and how other water molecules interact with another)
A polar molecule: The opposite ends of the molecule have opposite charges (dipolarity)
Polar covalent bonds form WITHIN water molecules (between oxygen and hydrogen atoms)
Unequal sharing of electrons
Due to electronegativity of oxygen
Oxygen becomes slightly negatively charged, and hydrogen atoms become slightly positively charged
The polarity of water molecules allows them to form hydrogen bonds with other water molecules (up to 4 per molecule) and with other polar (charged) substances
Thermal Properties of Water (Due to Hydrogen Bonds)
- High Specific Heat (Water can absorb or give off A LOT of heat without changing its own temperature very much)
Specific heat: the amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1 degree Celcius. It is a measure of how well a substance resists changing its temperature when it absorbs or releases heat.
The specific heat of water is 1 cal/g/ºC, which is extremely high
Why so high?!?
HYDROGEN BONDS! Hydrogen bonds absorb heat and break. Hydrogen bonds also release heat when they form.
As water molecules absorb heat, the hydrogen bonds between these molecules break before the water molecules themselves can begin absorbing heat and moving faster. Therefore, water molecules can absorb much more heat before their total kinetic energy – due to motion – is impacted by the heat absorption, allowing bodies of water to gain large amounts of heat without changing its own temperature very much! - High Heat of Vaporization (Water molecules absorb A LOT of heat when they evaporate)
Evaporation (or vaporization) is transformation of a substance from liquid to gas
Heat of vaporization is the amount of heat a liquid must absorb for 1 g of it to be converted to gas
Water has a HIGH heat of vaporization because of its… HYDROGEN BONDS!
A great deal of heat must be absorbed by water in order to break the hydrogen bonds between the molecules before any individual molecules can absorb enough heat to “escape” and move into the air.
Why is this important to life? Because it causes EVAPORATIVE COOLING: The “hottest” (fastest) molecules at the surface evaporate and take the absorbed heat (heat is absorbed from the body heat/ surface of the organism) with them, thus the new surface molecules that remain cool down (and cool the organism).
Transpiration (in plants), panting/ sweating (animals)
Adhesive Properties of water
Adhesion (the chemical attraction of one substance to a different substance) is also an important property of water
As it travels up the xylem (vascular tissue in plants), water forms hydrogen bonds with the cell walls (cellulose) of plants, helping to counter the effects of gravity (capillary action) as water molecules move up through a plant
Proverties of water compared to methane
Water and methane differ in thermal properties despite having similar structures (comparable weight, size, valence structure)
The differences are due to the polarity of water and its capacity to form intermolecular hydrogen bonds
Formula: CH4 H2O
Polarity: Nonpolar Polar
Heat Capacity –1 –1 (J.g .oC ): 2.2 4.186
Boiling Point (oC): -161 100
Solvent Properties of water
Water is a versatile solvent due to its POLARITY
“Like dissolves like” – Water dissolves:
The majority of all molecules found inside of and surrounding cells are polar (charged) – carbohydrates/ proteins/ nucleic acids/ enzymes
Inorganic charged particles (ions – ie: Na+, K+, Cl-)
Because water dissolves almost all of the molecules and particles needed for life, it is involved in almost all of chemical reactions in living organisms – it is the medium for metabolic reactions.
Explain the properties of water that are significant to life (and be able to compare these properties to methane)
The Structure of Water Provides it with Four Properties Which are Extremely Important to ALL Life as We Know It!
1. Cohesive Properties
2. Adhesive Properties
3. Thermal Properties
4. Solvent Properties
Cohesive Properties of water
Collectively, hydrogen bonds connect water molecules to other water molecules. The linkage of the same type of molecule by multiple hydrogen bonds is called cohesion, which:
1. Helps the transport of water against gravity in xylem of plants
Transpiration (evaporation of water from stomata) causes a “tug” on water molecules in the leaves, stems, and all the way down to the roots of plants, forming a water “column” through the vascular tissue (xylem) of plants
2. Causes spilled water to form into droplets
3. Allows water to have a high surface tension (certain organisms can live on
water surface)
4. Causes water to have a high boiling point (remains a liquid rather than a gas over global temp. range)
Know the cell theory (including evidence to support it and exceptions to refute it)
- All organisms composed of one (or more) cells
- Cells are the smallest units of life
- ALL cells come from pre-existing cells
Evidence:
-Living cells can be visualized using microscopes (since the 1600’s)
-No living organisms identified (to date) that are not made up of at least one cell
-Experimentation
Know the 7 basic functions of all life
Metabolism – chemical reaction that release energy for cellular use
Response – respond to internal/external stimuli
Homeostasis – maintain stable internal conditions
Growth – increase in cell size or cell number, grow/develop
Reproduction – produce more offspring/cells – sexually or asexually
Excretion – remove waste products
Nutrition – obtain energy/materials from environment
Know how to calculate cell sizes
(Mag = Manification size/ Actual size)
Conversions:
m to mm : 1 to 1000
m to cm: 1 to 100
m to um: 1 to 1x10^6
Explain the significance of surface area/ volume ratio to cells (and be able to explain what happens to this ratio as cell size increases/ decreases and identify this on a graph)
To Maintain a HIGH Surface Area to (low) Volume Ratio (SA/ V)
In general, as cell size increases, the surface area to volume ratio decreases (which is a bad thing) – WHY?
MORE surface area = more nutrients, oxygen etc. IN that the cell needs, and more wastes/ excess heat OUT that the cell does not need
So, cells “want” to maximize surface area (increased rate of material exchange)
The mass/ volume ratio of a cell determines the rate of heat and waste production and consumption of resources (metabolic reaction rate)
So, cells “want” to minimize volume (smaller volume = faster metabolic reaction rates)
Cells with more surface area PER unit of volume are able to move more wastes and heat out of the cell and more resources into the cell per unit of volume (making these cells more effective)
As a cell grows, its volume increases faster than its surface area, which decreases the SA/V ratio.
If metabolic rate is greater than exchange rate (nutrients/ wastes) the cell will eventually die
When cells become too large they divide (mitosis) to restore large SA/ V ratio to survive
Know what stem cells are, what characteristics they have that are important to life/ medicine, and how they differentiate (in multicellular organisms)
Stem cells are undifferentiated/ unspecialized cells with 2 key characteristics:
1. They can differentiate (into specialized cells)
2. They can continuously divide/ replicate (self renewal)
All cells in an early developing embryo are stem cells and are termed “totipotent”/ pluripotent” (toti = all, potent = potential, pluri = more), meaning that they are able to divide and become any type of cell (an important function in a developing embryo)
After birth (or germination in plants), only certain populations of stem cells remain, but with limited abilities. Stem cells post-birth/post-germination are only able to differentiate into tissue-specific cells within an organism (they are multipotent; multi = many)
Some cells in multicellular organisms lose the ability (or have a diminished ability) to reproduce once they differentiate during development
Example: Stargardt’s Disease
An inherited form of juvenile macular degeneration that causes vision loss to the point of blindness
Caused by a gene mutation that causes photoreceptor cells (rods/ cones) in retina to degenerate
Treated by replacing dead cells in the retina with functioning ones derived from stem cells
Be able to explain the process of therapeutic stem cell therapy
Stem cells can be used to replace damaged/ diseased tissues with healthy/ functioning cells
Therapeutic Stem Cell Therapy Process:
1. Expose stem cells to biochemical solutions in a lab to trigger their differentiation into the desired cell type
2. Surgically implant new cells into patient’s tissue
3. Suppress patient’s immune system to prevent rejection (if cells are from foreign source)
4. Monitor new cells for cancerous activity
Be able to discuss (both sides) the ethics of stem cell research
Ethical issues depend on the source of stem cells:
Using adult tissues is effective, but limited in application
Stem cells from newborns must be stored (at cost) – only those with the means for this benefit from it (issues of access/ availability)
Embryos provide the greatest amount of pluripotent stem cells, but acquiring them destroys a potential life, so…
When does life begin?
Does using embryonic stem cells “end” a life?
Is it better for excess embryos to be donated to science or to be disposed of as biohazard waste?
Which life is more valuable – that of an embryo with all of its potential or that of a human being already living its potential?
Is the suffering of an individual less important than the loss of an embryo?
Is the suffering of an embryo less important than the loss of an individual?
Are a human embryo and an individual equally important forms of life?
Know the characteristics of ALL cells
ALL cells (whether they are prokaryotic or eukaryotic):
Have a plasma (cell) membrane (phospholipid bilayer)
Contain a semifluid substance called cytoplasm/ cytosol (metabolic reactions)
Have one or more chromosomes (genes - DNA)
Have ribosomes (organelles that make proteins – NO membranes and made up of 2 subunits)
Compare prokaryotic and eukaryotic cells (similarities and differences)
Differences:
Prokariotic: DNA is naked (no proteins)
DNA is circular
DNA in nucleoid
DNA does NOT contain introns
No membrane-bound organelles/ no mitochondria
70S ribosomes
Smaller (size less than 10um)
Eukaryotic: DNA associated with proteins (histones)
DNA is linear
DNA in nucleus
DNA contains many introns
Membrane-bound organelles/ mitochondria
80S ribosomes
Larger (size more than 10um)
Similarities:
Both have DNA
Both have a cell membrane
Both have cytoplasm/ carry out all functions of life
Both contain ribosomes
Know which organelles are present in what cells and their functions (connect what organelles do to the difference processes that we have learned about this semester) also be able to answer questions about if an organelle is absent in a type of cell what will it be able to do and what will it not be able to do
Compare animal and plant cells (similarities and differences)
Differences:
Animals:
No cell walls (flexible/ rounded shape)
Centrioles
No chloroplasts
Small (if any) vacuoles
Carbohydrates stored as glycogen
Cholesterol in cell membrane
Plants
Cell walls (fixed, angular shape)
No centrioles
Chloroplasts
Large, central vacuoles
Carbohydrates stored as starch
No cholesterol in cell membrane
Similarities:
Similarities:
Both have DNA
Both have a cell membrane
Both have cytoplasm/ carry out all functions of life
Both contain ribosomes
Be able to draw/ identify prokaryotic cells, plant cells, animal cells, and their organelles.
Use notes
Explain the endosymbiotic theory (including the characteristics of mitochondria and chloroplasts that SUPPORT, not prove, it)
Theory States:
~2 billion years ago, a prokaryotic cell was engulfed (endocytosis) by primitive predatory/ heterotrophic cell
Symbiotic relationship formed (both benefited – mutualism), so both remained as ONE cell
- Euk. cells evolved from Prok. Cells!!!
MITOCHONDRIA and CHLOROPLASTS:
(These organelles ARE evidence for this theory!)
Have two membranes (original one and second one formed through endocytosis)
Have their own ribosomes (70S)
Divide by binary fission (independently of “host” cell)
Have their own DNA (circular/ naked)
About the same size as bacterial (prokaryotic) cells
Be able to diagram the cell membrane (2D only)
Use notes
Explain the properties of phospholipids that maintain the cell membrane
Know the functions of membrane proteins (in general)
Exocytosis (active)
Substances produced inside the cell (or its organelles) are processed and packaged in vesicles (surrounded by a phospholipid bilayer), which will fuse with the cell membrane and release their contents to the extracellular space (requires ATP)
In exocytosis: (hint: exo = “exit”)
Proteins produced by the rough endoplasmic reticulum are packaged in vesicles which “bud off” of the RER
Vesicles travel to the cis (same facing) side of the golgi apparatus and fuse with the membrane, “dumping” their contents into the golgi
Proteins move through the golgi and are processed/ modified. When they reach the trans (opposite) side of the golgi they are packaged into more vesicles which “bud off” the golgi
Vesicles move from the golgi to the cell membrane, fuse (phospholipid bilayer join) with membrane, and “dump”/ expel their contents out of the cell/ into the extracellular space (resulting in secretion of their contents from the cell and a slightly larger cell membrane)
Note: The fluidity of the cell membrane is essential to vesicle fusion (and subsequent secretion)
Examples of exocytosis: insulin (hormone) secreted from pancreatic cells; neurotransmitters secreted from neurons into synapse
Endocytosis (active)
The fluidity of the membrane allows it to change shape so parts of it can be “pinched off” (an infolding of the cell membrane) to form vesicles (small, membrane-bound structures in cells) around larger molecules/ fluids/ structures to move them into the cell (endocytosis)
When a vesicle enters a cell, the ends of the membrane that are left (where the membrane was pinched off) reattach due to the presence of water and the properties (hydrophilic and hydrophobic) of the phospholipids (this makes the cell’s membrane slightly smaller)
Phagocytosis is intake of large particles/ molecules/ organisms (“cell eating”)
Pinocytosis is intake of fluids (“cell drinking”)
Active Transport:
Active (against concentration gradient, ATP is required):
Substances move from areas of low concentration to areas of high concentration through protein pumps (against a concentration gradient)
Note: in active transport molecules are moved “against nature,” so energy – ATP – is required to make this happen
Examples: glucose reabsorption in kidney, glucose absorption in small intestine (ileum)
Simple Diffusion (passive)
Substances move from areas of high concentration/ high osmolarity (hypertonic solution) to areas of low concentration (hypotonic solution) to balance them out = move toward equilibrium (isotonic) – DOWN a concentration gradient
Note: diffusion is either directly through the phospholipid bilayer or through non-specific protein channels only gases, hydrophobic molecules and small polar uncharged molecules can do this (polar molecules and charged molecules cannot do simple diffusion)
Facilitated Diffusion
Diffusion of large molecules/ ions through highly specific protein carriers/ channels (proteins change shape to “facilitate” this – rate of transport levels off with saturation of proteins)
Osmosis (passive)
Osmosis (H2Osmosis!): Diffusion of water across membrane (through special protein channels called aquaporins); often to balance out solute concentrations (water moves from areas of low (hypotonic) solute concentration (high water) to areas of high (hypertonic) solute concentration (low water) to balance the solutes out)
Passive transport mechanisms
Include examples of each and be able to describe concentration gradients (hypertonic, isotonic, hypotonic).
Passive (along concentration gradient, no ATP expenditure):
concentration gradients:
Hypertonic: High solute concentration (gains water)
* Hypotonic: Low solute concentration (loses water) * Isotonic:Samesoluteconcentration(nonetflow)