BIOL 120 Mastering Assignments

One part of the cell theory states that all cells come from

preexisting cells

In Pasteur’s experiment, what would have happened if Pasteur had broken off the swan neck of the flask one week after boiling the nutrient broth to sterilize the flask

Cells from the air would have fallen into the sterilized growth medium and grown in there

What did Pasteurs results show?

When growth medium is not contaiminated by preexisting cells, the growth medium remains sterile

The cell theory states that all cells come from preexisting cells, If this is the case why are all the cells in multicellular organisms so different

Different genes are expressed in different cells to generate specific features

In comparison to Eukaryotes, prokaryotes

lack a nucleus, as do archaea, while eukaryotes have a nucleus

The common ancestry of life is evidenced by

near universality of the genetic code

This is true about natural selection

Natural selection favors individuals that reproduce more than others

Term that describes a trait that increases an individuals ability to survive a particular enviorment

Adaptations

How do offspring obtain traits from their parents

Heritability

Example of an organism that can be produced by artifical selection

A cow that produces a large quantity of milk

Pair of chickens that is likely to produce a large chicken

Large Chicken Large Chicken

Process of Natural Selection

In a given environment, specific versions of heritable traits help individuals survive better and reproduce more

What does it mean to say that a characteristic is heritable

Can be passed off to offspring

What would researchers have to do to convince you they had discovered life on another planet

It acquires and uses energy, replicate and have evolving populations

Natural Selection works only on traits that are

Heritable

What does it mean to say that experimental conditions are controlled

All physical conditions except for one are identical for all groups tested

Scientific experiments must be

Well documented and yield useful results regardless of whether or not hypothesis is accepted

Why do we control all variables except one

To eliminate alternative results of an experiment

Can “The first living cell on earth came from outer space” be tested

No

What is the fundamental purpose of a scientific experiment

To support or reject a hypothesis

What variable did Pasteur change in his experiment

Shape of the flask

Why did Pasteur boil broth in both flasks

To kill any existing organism in both

Supposed the sub-hypothesis that wing waving alone reduces predation by jumping spiders was supported by the Zonosemata experiment. What results support this

Zonosemata flies with house fly wings are attacked less frequently

Suppose that Zonosemata flies whose own wings had been clipped and reattached were attacked more frequently than untreated Zonosemata flies. How does this result affect the reliability of other experimental results

All results involving wing surgery are invalid

Which polymers are composed of amino acids

Protiens

Basic ammino acids include

A carboxyl function group, A side chain and an amino functional group

What part of an amino acid is always acidic

Carboxyl function group

What monomers make up RNA

Nucleotides

True or False, Enzymes in the digestive tract catalyze hydrolysis reactions

true

Which two functional groups are bound to the central carbon of every free amino acid monomer

an Amino group and a carboxyl group

Rank these from most hydrophilic to most hydrophobic, valine, aspartate, asparagine and tyrosine

Aspartate, asparagine, tyrosine, valine

What is unusual about the peptide bond compared to the other covalent bonds that form the polypeptide backbone

Peptide bonds behave like double bonds in terms of stability and lack of movement of atoms around the bond

Side chains of amino acids can be

polar or nonpolar

At about PH 7 of most cells, what happens to the amino group on an amino acid

It acts as a base and gains a protein, giving it a positive charge

The bonding of two amino acid molecules to form a larger molecule requires the

release of a water molecule

Which part of an amino acid varies among different amino acids

the side group / r groupPr

Proteins are polymers of

Amino Acids

What type of bond joins the monomers in a proteins primary structure

peptide

The secondary structure of a protein results from

hydrogen bonds

Primary structure is linked together by

peptide bonds

what type of bond is directly involved in the formation of an alpha helix

Hydrogen bonds between amino acids

What type of interaction stabilizes the alpha heliz and the beta pleated sheet structures of protiens

hydrogen bonds

What level of structure would be preserved if you disrupt all hydrogen bonds in a protien

Primary Structure

You are studying a protien that is shaped like a doughnut, the shape is a function of what levels of structure

primary, secondary and teritary

The tertiary structure of a protein is the

unique 3d shape of the fully folded peptide

What type of covalent bond between a amino acid side chains functions in maintaining a polypeptides 3d shape

Disulfide bond

What are prions

misfolded versions of proteins that can cause disease

Defensive proteins are manufactured by what system

immune system

What are the four nitrogenous bases found in DNA

Adenine, Thymine, Guanine, Cytosine

Nucleic acids are polymers made up of which monomer

nucleotides

What is the difference between a ribonucleotide and a deoxyribonucleotide

Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit

When nucleotides polymerize to form a nucleic acid..

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

The difference between sugar in RNA and DNA is that the sugar in DNA

contains one less oxygen atom

by convention, nucleotide sequences are always written from

the 5 prime end to the 3 prime end

Glycogen is

a polysaccharide found in animals

glucose + glucose —> ___ by ___

maltose + water, dehydration synthesis

Source of Lactose

milk

Example of polysaccharide

cellulose

__ is the most abundant organic compound on earth

cellulose

Ionic Bond

a chemical bond resulting from attraction between atoms that have a charge due to gaining or losing an electron

Covalent bond

a chemical bond in which two atoms share valence electrons

Hydrogen bond

is a weak chemical bond when the positively positive hydrogen atom of a polar covalent bond in one molecule is attracted to the partially negative atom of a polar covalent bond in another molecule

Surface Tension

How difficult it is to stretch or break the surface of a liquid

Adhesion

is an attraction between different kinds of molecules

Cohesion

is an attraction between like molecules

What type of bond is joining these two hydrogen atoms

covalent

Molecule

Two or more atoms held together by covalent bonds

Atoms with the same number of protons but different electrical charges

are different ions

In salt, what type of bond joins sodium and chlorine

ionic

An ionic bond involves

an attraction between ions of opposite charge

The innermost shell of an atom can hold up to how many atoms

2

An uncharged atom has what ratio of protons to electrons

1:1

What determines the types of chemical reactions that an atom partipates in

the number of electrons in the outermost electron shell

Why is oxygen more likely to form a polar covalent bond than other elements

It has a high electronegativity and holds shared electrons more tightly than other atoms

Electrons in valence shells are shared between atoms happens when

Covalent bonds are formed

Which 4 elements make up 96% of life

Carbon, Hydrogen, Nitrogen, Oxygen

Each element has a distinctive

number of protons

Knowing the atomic mass of an element allows inferences about

The number of protons and neutrons

A covalent chemical bond is one in which

outer shell electrons of two atoms are shared to fill their orbitals

Bonds between atoms that are equally electronegative are

nonpolar covalent bonds

a covalent bond is likely to be polar when

one of the atoms is more electronegative than the other

Where is a bacterial cells DNA found

nucleoid region

In a bacterium where are proteins synthesized

ribosomes

What is the rigid structure that is found outside the plasma membrane

cell wall

The —- is a bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and waste to leave

plasma membrane

A prokaryotic cell does not have a

endoplasmic reticulum

large numbers of ribosomes are present in cells that specialize in producing

protiens

What about mitochondria and chloroplasts suggest they were once free living bacteria

Produce their own ribosomes, have their own chromosomes, replicate individually of cell divison

A cell with a predominance of free ribosomes is most likely

primarily producing proteins in the cytosol

what type of organelle is primarily involved in the synthesis of oils, phospholipids and steroids

smooth er

What is the site that synthesizes proteins to be exported

rough er

What produces and modifies polysaccharides that will be secreted

Golgi Apparatus

What organelle contains hydrolytic enzymes

lysosomes

What organelle takes up most of a plant cell

vacuole

What organelle is the primary site of ATP synthesis in eukaryotic cells

mitochondrion

what plant cell organelle contains its own DNA and ribosomes

mitochondrion

Thylakoids, DNA and ribosomes are all components found in

chloroplasts

a cell with an extensive area of smooth er is specialized to

synthesize large quantities of lipids

Eukaryotic cells have more —- than prokaryotes

intercellular organelles

What leaves the nucleus of a Eukaryotic cell through pores in the nuclear membrane

mRNA