Biological Sciences - Exam 1

Atomic Number

Number of protons in an atom, always the same for each element

Atomic Mass

Teh combined weight of the protons and neutrons in an atom

Isotopes

Different forms of the same element (same number of protons, different number of neutrons)

Which types of atoms form covalent bonds with one another?

nonmetal

What makes a covalent bond polar

Unequal sharing of electrons (difference in electronegativity)

Which types of atoms form ionic bonds with eachother?

Metals and nonmetals

Hydrogen bonds

formed when a hydrogen atom that is already covalently bonded in one molecule bonds to an O, N, or F atom in a DIFFERENT MOLECULE

Why do hydrogen bonds form between water atoms

hydrogen (partial positive charge) in one water molecule attracts to oxygen (partial negative charge) in another water molecule

How are hydrogen bonds responsible for water’s resistance to change in temp.?

It requires a lot of energy to break hydrogen bonds, meaning it requires a lot of energy to change the temp. of water

How do hydrogen bonds in water store/ release heat energy?

Because hydrogen bonds are so hard to break, water absorbs a lot of energy before changing temp. This also means that water can release a lot of energy with minimal temp. changes.

Polarized molecules relation to water

hydrophilic, can dissolve

Non-polar molecules relation to water

Hydrophobic, can’t dissolve

What is the measurement for concentration of solute molecules?

Molarity (mol/L)

When an acid is dissolved in water, what ions does it release?

H+

When a base is dissolved in water, what ions does it release?

OH-

A solution is considered alkaline if…

There are more OH- ions than H+ ions

A solution is consdiered a

What pH values are considered acidic?

Lower than 7

What pH values are consider basic?

above 7

pH=

-log(H+)

Why is carbon the perfect basis for large, complex biological molecules

Because it has four valence electrons (potential to form four covalent bonds)

What are Hydrocarbons?

Organic compounds that are ONLY made of Hydrogen and Carbon

Why don’t hydrocarbons absorb in water?

They are nonpolar (hydrophobic) in nature

What are the 7 functional groups that are most important in the chemistry of life?

Hydroxyl, Carbonyl, Carboxyl, Sulfhydryl, Phosphate, Amino, Methyl

Hydroxyl

Adds polarity to molecules

Carbonyl

Adds polarity to molecules

Carboxyl

Acidic: donates H+ ion

Amino

Basic in aqueous solutions: takes H+ out of solution. Becomes Nh3+

Sulfhydryl

Adds polarity; Contribute to stability of proteins,

Phosphate

Facilitates energy transfer, massive polarity allows it to interact with water and other polar moelcules

Methyl

Only non-polar common functional group

What makes two molecules isomers of each other?

Same molecular formula but different arrangement or atoms

What are the four major biological macromolecules?

Lipids, polysaccharides, proteins, Nucleic Acids

Which biological macromolecule(s) are/ is NOT A POLYMER

Lipids

Which biological macromolecule(s) are/ is a POLYMER

Polysaccharides, proteins, nucleic acids

What is a dehydration reaction?

A chemical process where monomers combine to form polymers by removing a water molecule.

What is hydrolysis?

A chemical process that breaks down polymers into monomers by adding a water molecule to break down covalent bonds.

Prokaryotic cells example(s)

bacteria

Eukaryotic cells example(s)

plants, animals, fungi, protists

What are the cellular components required in all cells?

plasma membrane, cytosol/ cytoplasm, chromosomes, ribosomes

Chromosomes function in cells

carry genes

Ribosomes function in cells

make proteins

What do eukaryotic cells have that prokaryotic cells lack?

nucleus and internal membrane-bound organelles

What are cellular membranes made out of?

phospholipids in a liposome shape

What is a liposome?

Polar heads and nonpolar tails of lipids associate with one another in a bilayer

What is the importance of a selectively permeable membrane?

Allows for only certain substances to pass through while blocking others.

What molecules can pass right through the cellular membrane?

hydrophobic (nonpolar) ones

What molecules can pass through with the help of membrane proteins but without the expenditure of energy?

small polar ones

What molecules require the expenditure of energy to cross the membrane?

Large polar ones

How do hydrophobic (polar) molecules pass through the membrane?

easily, through simple diffusion.

The phospholipid bilayer’s hydrophobic tails ______ water-soluble and charged substances from passing freely

prevent

What is active transport?

Moves substances against their concentration gradients, requires ATP, performed by specific proteins embedded in the membrane (pumps)

What is passive transport?

molecules move across the cell membrane without expending energy, driven by the concentration gradient (high to low concentration)

Passive transport examples

Simple diffusion, facilitated diffusion, osmosis

Facilitated Diffusion

transport proteins speed the passive movement of molecules across the plasma membrane

Tonicity

The ratio of solute concentration inside the cell vs outside the cell

Isotonic Solution

Solute concentration is the same as that inside the cell; no net movement across the membrane

Hypotonic Solution

Solute concentration is less than inside the cell; cell gains water

Hypertonic Solution

Solute concentration is greater than that inside the cell; cell looses water

Exocytosis

transport vesicles migrate to the membrane, fuse with it, and release their contents

Endocytosis

The cell takes in macromolecules by forming vesicles from the plasma membrane

Bulk Transport

Endocytosis, exocytosis, requires energy

Endomembrane system

has separate cell structures that allow specific functions to take place within defined places in the cell

Rough Endoplasmic Reticulum

Associated with ribosomes, which help with protein synthesis and modification

Smooth Endoplasmic Reticulum

Lacks ribosomes, primary sight of lipid synthesis

Golgi Apparatus

cisternae carry proteins or modified sugars to the membrane or organelles, enzymes chemically modify proteins and lipids

Lysosomes

vesicles derived from Golgi, degrade damaged or unneeded macromolecules, maintain a pH of 5, contain hydrolytic enzymes that break down molecules

What do mitochondria and chloroplasts have in common?

not included in endomembrane system, grow and multiply independently from rest of the cell, contain their own DNA in circular genomes

Mitochondria

convert chemical potential energy from organic molecules (sugar, fat) into ATP

Chloroplasts

Capture energy from sunlight to convert CO2 gas into larger organic molecules