Bio 101 Lessons 1-8

Characteristics that define all life

* Order
* Reproduction
* Growth & Development
* Response to the Environment
* Energy Processing
* Regulation
* Evolutionary Adaptation

What is the smallest unit of life?/ At which level of interaction does life first appear?

The cell ; Life emerges from the ordered interactions of the structure of the cell.

Life’s hierarchy of organization

1. Biosphere
2. Ecosystem
3. Community
4. Population
5. Organism
6. Organs and Organ Systems
7. Tissue
8. Cell
9. Organelle
10. Molecule

Emergent Properties

Individual tissues can have specific functions, but when put together with other tissue types in certain configurations in organs, new functions arise

Quantitative Data

Generally numerical measurements

Qualitative Data

Generally in the form of recorded descriptions

Hypothesis

A proposed explanation for a set of observations

* leads to an experiment that we can test
* cannot be proven as true

Experiment

Scientific test carried out under controlled conditions

Theory vs. Hypothesis

A theory is much broader in scope and it’s supported by a large, usually growing body of evidence

How is science different from other ways of describing and explaining nature, such as philosophy and religion?

The scientific view of the world is based on hypothesis testing and verifiable evidence

What is the main requirement for a scientific hypothesis?

It must generate predictions that can be tested by experiments of gathering further observations.

Independent variables

manipulated by the researcher

dependent variable

the measure used to judge the outcome of the experiment

control groups

differ in only the one variable the experiment is designed to test compared to the experimental group

Predictions

if…then statements

ex:

If camouflage coloration protects mice from predators, then mice that matched their environment would be preyed on less frequently than mice with coloration that didn’t match their habitat

observational study

An observational study is a type of research design where researchers observe and analyze individuals or groups without intervening or manipulating any variables. The goal is to gather data and draw conclusions about the relationship between variables or phenomena

Process of Science (repetitive, nonlinear, and collaborative)

Exploration & discovery: Observing/asking questions, reading literature

Formation & testing of hypotheses: Collecting/interpreting data

Societal benefits & outcomes: Solving problems, developing new technologies

Feedback from the Scientific community: Peer reviewed publications, replication of findings, consensus building

What is a Scientific Theory vs. a Hypothesis vs. a Law?

A law is descriptive. But a hypothesis and a scientific theory seek to explain

5 Unifying Themes of Biology

1. Evolution
2. Flow of information
3. Structure and Function
4. Transformation of matter and energy
5. Interactions within and between systems

Evolution

the process of change that has transformed life on Earth from its earliest forms to the vast array of organisms living today

Flow of Information

the integrated flow of genetic and other types of information (genetic information encoded in DNA determines an organism’s structures and functions; such properties also depend on the stimuli, signals, and pathways that regulate where, when, and how an organism’s genetic information is expressed)

Structure and Function

in biological systems, structure (the shape of something) and function (what it does) are almost always related, with each providing insight into the other

Transformation of matter and energy

the input of energy, primarily from the sun and the conversion of energy from one form to another make life possible

Interactions within and between systems

the emergent properties of each level of the hierarchy of life result from the specific arrangement and interactions of its parts (your body is a system and it is the interactions between the parts (molecules, cells, tissues, organs) that allow you to maintain a relatively stable internal environment

What is an organic compound?

A carbon based molecule; usually contains hydrogen atoms in addition to carbon

ex: Glucose

hydrophilic

water loving

What chemical groups can be found contained in the building blocks of proteins?

An amino group and a carboxyl group

Monomers of carbohydrates

Monosaccharides

ex: glucose and fructuose

The use of sugars as both energy resources and organic building blocks clearly illustrates one of our five themes of life, which one?

Energy and Matter

Describe how two monosaccharides are joined and what forms when they are chemically joined.

Two monosaccharides are joined using a dehydration reaction thus forming a disaccharide

Starch

* found in plants
* function: can withdraw glucose for energy or building materials

glycogen

* found in animals
* function: for energy storage

cellulose

* found in plants
* Structural function (plant cell walls)

Hydrolysis

Hydrolysis is a chemical reaction that involves the breaking of a chemical bond in a molecule through the addition of water. . This reaction can result in the decomposition of complex molecules into simpler ones.

Dehydration reaction

A dehydration reaction is a chemical reaction in which water molecules are removed from a compound or a molecule, resulting in the formation of a new compound. Dehydration reactions are commonly involved in the synthesis of larger molecules, such as proteins, carbohydrates, and nucleic acids. They are often catalyzed by enzymes and require energy input.

hydrophobic

water fearing

What, if any, are the monomers of fats?

Glycerol/fatty acids

Compare and contrast unsaturated and saturated fats in terms of where they can be found (plant or animal).

Most animal fats are saturated: their hydrocarbon chains- the “tails” of their fatty acids- lack double bonds and thus pack closely together, making them solid at room temperature. In contrast the fats of plants and fishes generally contain unsaturated fatty acids (the kinks in their tails prevent them from packing tightly together thus unsaturated fats are usually liquid at room temperature and are referred to as oils

What is the main function of fats?

Energy Storage

Phospholipid structure

Hydrophilic head and hydrophobic tails

What are the monomers of proteins

amino acids

Denaturation

When a protein unravels or unfolds

A proteins’ function depends on:

its unique shape

There are 20 different amino acids, what part of each amino acid makes it different from the other amino acids?

Its R group (hydrophobic amino acids have nonpolar R groups; the R group of hydrophilic amino acids on the other hand, may be polar or charged.) Hydrophobic amino acids may cluster together in the center of a globular protein while hydrophilic amino acids face the outside helping proteins dissolve in the aqueous solution of a cell.

Primary structure of Protein

Amino acid sequences join together through a dehydration reaction. The covalent bonds between amino acids are known as peptide bonds

Secondary structure of Protein

hydrogen bonds between the amino group of one amino acid and the carboxyl group of another amino acid. Two types of secondary structure occur: alpha helices and beta pleated sheets

Tertiary structure of a Protein

The three-dimensional structure of a protein

Why do only some proteins have quaternary structure?

They are only found in proteins that have two or more interacting polypeptide chains, termed subunits

What are the monomers of DNA called? Does RNA have different monomers?

The monomers of DNA and RNA are called nucleotides. Each DNA nucleotide has one of four different nitrogenous bases: adenine, thymine, cytosine, and guanine. RNA nucleotides also contain the bases A,C, and G; but the base uracil is found instead of thymine.

The DNA sugar-phosphate backbone is held together by covalent bonds. What kinds of bonds hold the two strands of the double helix together?

Hydrogen bonds between their paired bases hold the two DNA chains together

Which of the four macromolecule groups does fiber fall under? What are the three other macromolecule groups?

Fiber is classified as a polysaccharide making it fall under the carbohydrate group. The other three groups are fats, protein, and nucleic acid

What holds a protein’s structure together? What can disrupt this structure?

The chemistry of the R groups is allowing or promoting them to interact/fold (imagine one is positively charged and one is negatively charged) Mutations can disrupt the structure/ incompatible R groups

Why can’t cells get very big?

The maximum size of a cell is influenced by the need to have a surface area large enough to service the volume of a cell.

As cell size increases, what happens to its surface-to-volume ratio?

It’s surface to volume ratio decreases (combined smaller cells have a much greater surface to volume ratio than larger cells)

What is the structure and function of the plasma membrane?

The plasma membrane aka the cell membrane forms a flexible boundary between the living cell and it’s surroundings. As a structure it separates life from non-life with its thin membrane.

Phospholipids group together to form a two-layer sheet called a phospholipid bilayer (the hydrophilic heads face outward exposed to aqueous solutions on both sides of a membrane while the hydrophobic tails point inward shielded from water. Embedded in the lipid bilayer are diverse proteins. the properties of the phospholipid bilayer and the proteins suspended in it relate to the plasma membrane’s job as a traffic cop, regulating the flow of material into and out of the cell.

Prokaryotic cells

Prokaryotic cells are simple, single-celled organisms that lack a nucleus and other membrane-bound organelles. They are typically smaller and less complex than eukaryotic cells. Prokaryotic cells are found in bacteria and archaea, and they have a circular DNA molecule floating freely in the cytoplasm. They also have a cell membrane and a cell wall for protection.

Eukaryotic cells

Eukaryotic cells have a true nucleus enclosed in a membrane. They are found in plants, animals, fungi, and protists. Eukaryotic cells have membrane-bound organelles like mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes. They also have a cytoskeleton for support and movement.

What features do all cells have in common?

Cytosol: thick jellylike fluid in the interior of all cells; cellular components are suspended in it

Chromosomes: carry genes made of DNA

Ribosomes: tiny structures that make proteins according to instructions from the genes

Cytoplasm: inside of both types of cells (in eukaryotic only refers to the region between the nucleus and the plasma membrane)

Eukaryotic vs. Prokaryotic cells

Eukaryotic cells have membrane enclosed nuclei and many membrane enclosed organelles that perform specific functions. Prokaryotic cells are smaller and simpler without membrane enclosed nuclei and they have flagella to help propel them

What is the advantage for the cell in having “compartments” within a eukaryotic cell?

the internal membranes of a eukaryotic cell partition it into functional compartments in which many of its chemical activities—collectively called cellular metabolism—take place. Various enzymes essential for metabolic processes are built into the membranes of organelles. The fluid filled spaces withing such compartments are locations where specific chemical conditions are maintained (conditions vary among organelles and favor the metabolic processes occurring in each.

Compare and contrast a plant cell and an animal cell. Examine diagrams of typical organelles of plant and animal cells, what differences do you see?

Except for lysosomes and centrosomes the organelles and other structures of animal cells are found in plant cells. Although some animals cells have flagella or cilia, among plants only the sperm cells of a few species have flagella. Plant cells have rigid, thick cells walls that animal cells don’t. An important organelle found in plant cells is the chloroplast, where photosynthesis occurs. Unique to plant cells is a large central vacuole, a compartment that stores water and a variety of chemicals.

DNA

The cell’s genetic instructions inside the nucleus

Nuclear Envelope

A barrier separating the cell’s genetic information from the cell’s cytosol

How materials enter and exit the nucleus

nuclear pores

DNA is transcribed into another set of “instructions”called ____ that directs protein synthesis?

mRNA

A cell with many ribosomes (*structural* characteristic) tells you what about this cell’s *function?*

The cell makes a lot of proteins

What is the difference between proteins that are made by free ribosomes in the cytosol or ribosomes attached to the endoplasmic reticulum or nuclear envelope?

Free and bound ribosomes are structurally identical, and they can function in either location, depending on the protein they are making. Most of the proteins made on free ribosomes function within the cytosol; examples are enzymes that catalyze the first steps of sugar breakdown for cellular respiration. bound leave the cell

The rough ER and Golgi form a functional unit that help to produce what for the cell?

As polypeptides destined to be membrane proteins grow from bound ribosomes, they are inserted into the ER membrane. Phospholipids are made by enzymes of the rough ER and also inserted into the membrane. Thus, the ER membrane grows, and portions of it are transferred to other components of the endomembrane system in the form of transport vesicles. After leaving the ER many transport vesicles travel to the Golgi apparatus. The Golgi apparatus serves as a molecular warehouse and processing station for products manufactured by the ER. The number of Golgi stacks correlates with how active the cell is in secreting proteins (a multistep process initiated in the rough ER. One side of a golgi stack serves as a receiving dock for transport vesicles produced by the ER; a vesicle fuses with a golgi sac adding its membrane and contents to the receiving side; products of the ER are modified as they progress through the stack; the “shipping side of the golgi functions as a depot dispatching its products in vesicles that bud off and travel to other sites.

What is the function of lysosomes?

A membrane enclosed sac of digestive enzymes; a lysosome provides an acidic environment for its enzymes while safely isolating them from the rest of the cell. They also serve as recycling centers for damaged organelles or small amounts of cytosol in vesicles, dismantling their contents and making their molecules available for reuse

What is one disease associated with malfunction of the lysosomal enzymes?

Tay-Sachs disease (a lipid-digesting enzyme is missing, and brain cells become impaired by an accumulation of lipids)

What is the function of mitochondria? Do prokaryotes, animal cells, or plant cells have mitochondria?

Mitochondria carry out cellular respiration in nearly all eukaryotic cells. Mitochondria are only found in eukaryotic cells so if a plant or animal cell is eukaryotic it has a mitochondria

All eukaryotes have mitochondria, but not all eukaryotes have chloroplasts. Can you propose an evolutionary explanation for this observation?

The endosymbiont theory states that mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells. These prokaryotes may have gained entry to the larger cell as undigested prey or parasites. If one of these cells acquired a photosynthetic prokaryote, the prokaryote could provide the host cell with nourishment. An increasingly interdependent host and endosymbiont, over many generations, could become a eukaryotic cell containing chloroplasts.

What is the function of the cytoskeleton?

The cytoskeleton provides structural support and aids in movement

What are three protein fibers that make-up the cytoskeleton?

Microtubules (thickest): straight, hollow tubes composed of globular proteins called tubulins. shape and support the cell and also act as tracks along which organelles equipped with motor proteins move



microfilaments (thinnest): also called actin filaments, are solid rods composed mainly of globular proteins called actin, arranged in a twisted double chain. Form a three-dimensional network just inside the plasma membrane that helps support the cell’s shape.



intermediate filaments (in between in thickness): made of various fibrous proteins that supercoil into cables. Intermediate filaments reinforce cell shape and anchor some organelles.

What does insulin normally do?

Insulin tells your cells to take up glucose from the blood.

What would happen to this system without insulin?

Insulin functions a bit like a key to a door. Without insulin the glucose transporters proteins will not make it to the surface of the cell and glucose will not enter a cell.

Why do type 1 diabetics have no insulin?

They don’t have the beta pancreatic cells that produce insulin. (Autoimmune function- the body deploys these cells). Without the beta cells you can’t make insulin and thus can’t lower glucose levels from your blood.

Type II diabetics have enough insulin (at least earlier in the disease). How could they have high blood sugar if they have enough insulin? What else could be “broken”?

The signaling that tells the glucose receptors to go to the cell surface is insufficient/not working

What might happen if a person injected themselves with too much insulin? What might be the consequence?

They might become hypoglycemic

Fluid mosaic (membrane)

diverse protein molecules suspended in a fluid phospholipid bi-layer

selective permeability

allows some substances to cross more easily than others

Why was the spontaneous formation of membranes such an important step in cell __evolution__?

A membrane that not only encloses a successful assembly of molecules but also regulates chemical exchanges with the environment is a basic requirement for life.

How does the structure of the membrane relate to its selective permeability? (Think about the chemical properties of the inner core of the bi-layer.)

The tails of the phospholipids are packed together tightly preventing any large molecules from diffusing through. Only small, nonpolar materials can move through the bilayer as the phospholipid tails of the membrane are nonpolar.

Can O2 and CO2 diffuse easily across a membrane? Why or why not?

Yes because they are small nonpolar molecules

What do ions and polar molecules need to diffuse across the hydrophobic interior of a membrane?

They need transport proteins and they need to move down their concentration gradients.

Osmosis

When water moves through a selectively permeable membrane down its concentration gradient

If I give you a 5% sucrose solution and a 10% sucrose solution, in which solution is the free water less concentrated?

The 5% sucrose solution

If the 5% and 10% solution were separated by a semi-permeable membrane that sucrose could not move between, the water would move ________ the 10% solution.

to

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

Tonicity of a solution is dependent on:

its concentration of solutes relative to the concentration of solutes inside the cell

Isotonic

a solution that, when surrounding a cell, causes no net movement of water into or out of the cell

hypertonic

a solution that, when surrounding a cell, will cause the cell to lose water (higher solute concentration)

Hypotonic

A solution that, when surrounding a cell, will cause the cell to take up water (lower solute concentration)

If a cell is put into a solution that is hypertonic to its cytosol, what would happen? (shrink or swell?) Why? Where is the water more concentrated?

It will shrink as the water is more concentrated in the hypertonic solution due to its higher solute concentration

How is facilitated diffusion similar and different from diffusion?

Facilitated diffusion is assisted by the help of specific transport proteins that allow hydrophilic molecules and ions to move across the membrane (still passive because it doesn’t require energy. Diffusion doesn’t require any assistance from proteins etc.

What kind of transport does glucose use?

Facilitated diffusion

Water is a *polar* molecule, but it is very small so it can diffuse slowly into cells. What type of membrane protein would you expect to find in a cell to make it highly permeable to water?

an aquaporin

Active Transport

Uses energy and transport proteins to move against the concentration gradient

exocytosis vs. endocytosis

Exocytosis exports bulky materials out of the cell while endocytosis take in larger molecules into the cell.

Phagocytosis

A cell engulfs a particle by wrapping extensions called pseudopodia around it and packaging it within a membrane-enclosed sac called a vacuole. The vacuole then fuses with a lysosome, whose hydrolytic enzymes digest the contents of the vacuole