biology unit 2 test
What structure is only found in prokaryotic cells?
nucleoid
what is this
phosphate group
what is this
glycerol
Explain the difference between saturated and unsaturated fatty acids?
A fatty acid whose hydrocarbon chain contains one or more double bonds is called an unsaturated fatty acid. Each carbon atom connected by a double bond has one fewer hydrogen atom attached to it. These double bonds usually cause kinks (or bends) in the carbon chain. A fatty acid that has no double bonds in its hydrocarbon chain has the maximum number of hydrogen atoms attached to each carbon atom (its carbons are "saturated" with hydrogen) and is called a saturated fatty acid.
Define the term amphipathic and explain why phospholipids are amphipathic
A phospholipid is an amphipathic molecule which means it has both a hydrophobic and a hydrophilic component. A single phospholipid molecule has a phosphate group on one end, called the "head," and two side-by-side chains of fatty acids that make up the lipid "tails.
A scientist wants to magnify a pollen grain 800 times and examine the ridges and pores of its surface. Which instrument would be best?
A scanning electron microscope
active transport
Active transport requires the cell to expend energy active transport uses ATP as an energy source active transport can move a solute against its concentration gradient
True or false regarding carbon? a) Carbon has the ability to bond with up to six other atoms. b) Carbon has the capacity to form single and double bonds. c) Carbon has the ability to bond to form extensive branched or unbranched carbon skeletons. d) Carbon has a tendency to form covalent bonds.
All are correct except for a. Carbon has a tendency to form covalent bonds. A carbon cannot form 6 bonds with other atoms. A carbon has 6 electrons including two in the first shell, and four in the second shell, its valence shell. In order to fill its second shell carbon tends to form covalent bonds with other atoms. Because there are four electrons in its second shell, and a fall shower would contain eight electrons, Carbon can only share electrons with up to four other atoms.
Cell theory states that...
All living things are composed of cells and that cells come from other cells.
You are told that the cells on a microscope slide are plant, animal, or bacterial. You look at them through a microscope and see cell walls and membrane-bound organelles. You conclude correctly that the cells
Are plant cells. plant cells contain both a cell wall and membrane-bound organelles. For example, in plant cells chloroplasts, a membrane-bound organelle, function in energy processing.
active transport - Type of solute - nonpolar OR polar/charged - Example solutes - Protein required - YES OR NO - The direction of solute movement - with OR against concentration gradient - Energy required - YES OR NO
Both - mostly polar moving Na+ out of the cell and K+ into the cell. Yes to move a solute against its concentration gradient Yes
Explain how carbon atoms can join together to create diverse carbon skeletons? What types of carbon skeletons can form?
Carbon chains form the backbone of most organic molecules. They may differ in length and can be straight, branched, or arranged in rings. Carbon skeletons may also include double bonds, which can vary in number and location.
Explain what an organic compound is?
Carbon-based molecules are called organic compounds and they usually contain hydrogen atoms in addition to carbon. Carbon is unparalleled in its ability to form large and complex molecules, which build the structures and carry out the functions required for life.
Explain how dehydration synthesis reactions join together components to make a phospholipid molecule?
Dehydration is the process of removing water. Synthesis is to form something by combining parts. Both reactions yield 3 molecules of water and use glycerol and fatty acid reactants. Three fatty acids are needed to form a triglyceride while two fatty acids and a phosphate head are needed to form a phospholipid.
The division of a cell's interior in two separate membrane enclosed compartments allows...
Different chemical conditions to be maintained in different parts of the cells. It makes the cell more efficient
Describe hydrolysis
Essentially the reverse of a dehydration reaction, hydrolysis means to break (lyse) with water (hydro-). As the right side of shows, the bond between monomers is broken by the addition of a water molecule, with the hydroxyl group from the water attaching to one monomer and hydrogen attaching to the adjacent monomer. - used in digestion
Identify at least two reasons why it is important that membranes are fluid? (fluid mosaic model for membrane structure) Why are they fluid?
Fluidity is important for many reasons. it allows membrane proteins rapidly in the bilayer and It permits membrane lipids and proteins to diffuse from sites where they are inserted into bilayer after their synthesis. To work properly with active enzymes and appropriate permeability, membranes must be about as fluid as salad oil. A membrane is held together primarily by hydrophobic interactions, which are much weaker than covalent bonds. Most of the lipids and some of the proteins can shift about loosely, that is, in the plane of the membrane, like partygoers elbowing their way through a crowded room.
Explain how the presence of a carbon-carbon double bond affects the shape of a molecule?
It makes it flat. This double carbon bond can vary in location.
Define the term selective permeability?
Like all biological membranes, the plasma membrane is selectively permeable, allowing some substances to cross more easily than others. It controls traffic into and out of the cell it surrounds.
Identify the properties that are shared by all lipids?
Lipids are a diverse group of molecules that are classified together because they share one trait: They do not mix well with water. In contrast to carbohydrates and most other biological molecules, lipids are hydrophobic
Distinguish between magnification and resolution
Magnification is the increase in an object's image size compared with its actual size. An important factor in microscopy is resolution, a measure of the clarity of an image. Resolution is the ability to distinguish two nearby objects as separate. For example, what you see as a single star in the sky may be resolved as twin stars with a telescope.
Define diffusion
Molecules have a type of energy called thermal energy, due to their constant motion. One result of this motion is diffusion, the tendency for particles of any substance to spread out into the available space.
Diffusion - Type of solute - nonpolar OR polar/charged - Example solutes - Protein required - YES OR NO - The direction of solute movement - with OR against concentration gradient - Energy required - YES OR NO
Nonpolar CO₂ and O₂ No down the concentration gradient No
Explain the role of transport proteins in establishing the selective permeability of a membrane?
One type of transport protein provides a channel that specific molecules or ions use as a passageway through a membrane. Another type of transport protein, called a carrier protein, binds its passenger, changes shape, and releases the transported molecule on the other side. In both cases, the transport protein helps a specific substance diffuse across the membrane down its concentration gradient and, thus, requires no input of energy. They contribute to membranes selective permeability Because they are specific for the solutes they transport, the numbers and kinds of transport proteins affect a membrane's permeability to various solutes.
Identify the components of a phospholipid.
Phospholipids are structurally similar to fats, except that they contain only two fatty acids attached to glycerol instead of three. The interactions between phospholipid molecules within a watery environment result in their arrangement into a double-layered sheet. The hydrophobic tails of the phospholipids cluster together in the center of the sheet, excluded from water, and the hydrophilic phosphate heads face the watery environment on either side of the resulting membrane.
Describe why polar and charged solutes have difficulty passing through a biological membrane
Polar molecules can easily interact with the outer face of the membrane, where the negatively charged head groups are found, but they have difficulty passing through its hydrophobic core. ... Larger charged and polar molecules, like sugars and amino acids, also need help from proteins to efficiently cross the membrane.
Resolution is
The ability of an optical instrument to show two close objects as separate
Identify which eukaryotic organelles support the following cell functions? Carrying out genetic control of the cell? Manufacturing, distribution, and breakdown of molecules? Energy processing? Structural support, movement, and communication?
The nucleus and ribosomes carry out the genetic control of the cell Endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes. Mitochondria in all cells and chloroplasts in plant cells. The cytoskeleton, plasma membrane, and plant cell wall.
Explain why energy is needed for active transport?
To pump a solute across a membrane against its gradient requires work, the cell must expend energy. This membrane traffic is called active transport. The transport protein that moves solutes against the concentration gradient is all carrier proteins, rather than channel proteins.
facilitated diffusion across a biological membrane requires ____ and moves a substance ____ its concentration gradient
Transport proteins; down
As cell size increases, the...
Volume increases proportionally more than the surface area.
Explain how amphipathic nature of phospholipids allows them to form the bilayer that is Central to the member structure
When phospholipids are mixed with water, they spontaneously rearrange themselves to form the lowest free-energy configuration. This means that the hydrophobic regions find ways to remove themselves from water, while the hydrophilic regions interact with water. The resulting structure is called a lipid bilayer.
In a carbonyl group
a carbon atom is linked by a double bond to an oxygen atom. The carbonyl group can be located within or at the end of a carbon skeleton. A carboxyl group consists of a carbon double-bonded to an oxygen atom and also bonded to a hydroxyl group. the carboxyl group can act as an acid by contributing an H+ to a solution and thus becoming ionized. Compounds with carboxyl groups are called carboxylic acids.
describe dehydration reaction
a reaction that removes a molecule of water as two molecules become bonded together. Each monomer contributes part of the water molecule that is released during the reaction. One monomer loses a hydroxyl group and the other monomer loses a hydrogen atom to form H2O. As this occurs, a new covalent bond forms, linking the two monomers. Dehydration reactions are the same regardless of the specific monomers and the type of polymer the cell is producing. Cells link monomers together to form polymers by a dehydration reaction
true or false about dehydration reactions... a) Animal digestive systems utilize this process to break down food. b) One monomer loses a hydrogen atom, and the other loses a hydroxyl group. c) H2O is formed as the monomers are joined. d) Covalent bonds are formed between the monomers.
all are true besides a. Answer A is false because animal digestive systems do not use this process to break down food. You must digest polymers to make their monomers available to your cells. However, digestive systems use hydrolysis reactions, which are essentially the reverse of dehydration reactions.
what is this
amino
what is this
carbonyl
what is this
carboxyl group
what is this
carboxylic acid
A methyl group
consists of a carbon bonded to three hydrogen atoms. The methylated compound in the table— a component of DNA—affects the expression of genes.
A hydroxyl group
consists of a hydrogen atom bonded to an oxygen atom.
A phosphate group
consists of a phosphorus atom bonded to four oxygen atoms. It too is usually ionized, as you can see by the negatively charged oxygens in the figure. Compounds with phosphate groups are called organic phosphates and are often involved in energy transfers, as is the energy-rich compound ATP (adenosine triphosphate), shown in the table.
what is this
fatty acid
An amino group
has nitrogen bonded to two hydrogens. It can act as a base by picking up an H+ from a solution and becoming ionized. Organic compounds with an amino group are called amines. The building blocks of proteins—amino acids—contain an amino and a carboxyl group.
what is this
hydroxyl
Explain what isomers are?
isomers are what makes polymers. Compounds with the same formula but different structural arrangements are called isomers. The different shapes of isomers add greatly to the diversity of organic molecules and their properties. Isomers can also result from the different spatial arrangements that can occur when four different partners are bonded to a carbon atom
what is this
methyl group
facilitated diffusion - Type of solute - nonpolar OR polar/charged - Example solutes - Protein required - YES OR NO - The direction of solute movement - with OR against concentration gradient - Energy required - YES OR NO
polar/charged Hydrophilic molecules and ions Yes driving force is the concentration gradient No
explain that the addition of chemical groups to a carbon skeleton has a large impact on the chemical properties of a molecule?
small differences affect how the molecule's function. for example, we see that the addition of one small chemical group to a carbon skeleton can change the entire hormone itself. The hormones testosterone and estradiol (a type of estrogen) differ only in the groups of atoms highlighted with colored boxes.
Why are cells so small?
surface area to volume ratio - At a minimum, a cell must be large enough to house enough DNA, protein molecules, and structures to survive and reproduce. The maximum size of a cell is influenced by geometry—the need to have a surface area large enough to service the volume of a cell.
plasma membranes are selectively permeable. this means that
the plasma membrane allows some substances to enter or leave a cell more easily than others
