Study Guide

Question 1

What does a Nucleotide molecule consist of:

Answer 1

nitrogenous base
5-carbon sugar
1+ phosphate groups

Question 2

4 different Nucleotides

Answer 2

ATP (Adenine)
GTP (Guanine)
TTP (Thymine)
CTP (Cytosine)

Question 3

Hydrogen Bonds role in Nucleic Acid

Answer 3

• allows ALL nucleotides to form secondary structures between nitrogenous bases
• hydrogen bonds formed by Complementary Base Pairing
• holds together 2 complimentary chains to form a double helix

Question 4

Covalent Bonds role in Nucleic Acid

Answer 4

• hold atoms in molecules together in each amino acid chains

- Phosphate of 1 nucleotide is covalently bound to the sugar of the next nucleotide

Question 5

DNA

Answer 5

• Sugar deoxyribose (H)
• Double-stranded molecule
• Stable under alkaline conditions
• Stores & transfers genetic info
• A,T,G,C

Question 6

RNA

Answer 6

• Sugar ribose (extra 0H group)
• Single-stranded molecule
• Not stable
• -Directly codes for amino acids
• Act as a messenger between DNA and ribosomes to make protein
• A, U, G, C
• Uracil lack metyl group in its ring

Question 7

Explain “5 prime”, “3 prime”?

Answer 7

The distinct ends of the molecule I referred to as the 5’end and the 3’ end reflecting the number of the carbon in the sugar

Question 8

Explain complementary base pairing

Answer 8

requires that the bases be oriented in a way that the facilitates the formation of the hydrogen bonds
-This can only happen if the two strands of nucleic acid are anti-parallel

Question 9

Explain what is anti-parallel

Answer 9

when two strands run parallel to each other but with opposite alignment

Question 10

Apply the idea of complementary base pairing to folding of DNA

Answer 10

DNA is well known as a double helix.

Two individual strands of DNA are held together by complementary base pairing.

Question 11

Define “semi-conservative replication”

Answer 11

DNA replication were each of the 2 daughter DNA molecules contains 1 intact strand of the parental DNA molecule in 1 continuous newly synthesized strand of DNA.

Question 12

Describe the role of the various proteins involved in DNA replication

Answer 12

• DNA helicase helps to unwind the DNA making it possible for the other proteins to gain access to the sequence
• Topoisomerase helps relieve the torsional stress (twist) that form because of the unwinding
• The Single Stranded Binding proteins help stabilize the DNA while it is unfolded and unattached
• DNA polymerase III catalyzes the formation of the new DNA strand using the original strand as it’s template

Question 13

Outline the steps of DNA replication

Answer 13

1. DNA ‘unzips’
2. DNA unwinds
3. The original DNA strands function as templates for the addition of new, complementary nucleotides
4. Covalent bonds link the nucleotides together
5. The process repeats until the entire molecule of DNA is copied

Question 14

Leading Strand Synthesis

Answer 14

synthesized in the same direction as the movement of the replication fork, and is synthesized continuously.

Question 15

Lagging Strand Synthesis

Answer 15

synthesized in the opposite direction and is synthesized in short fragments that are ultimately stitched together (okazaki fragments.)

Question 16

Describe how DNA is packaged and organized in a eukaryotic cell

Answer 16

• In most eukaryotes, chromosomes are linear, and multiple replication bubbles at different stages in the replication process are located along the chromosomes.

• The linear nature of eukaryotic DNA presents a challenge not typically found in bacterial DNA replication
o DNA polymerase III cannot add the final sequence of DNA to the 5′ end of the lagging daughter strand.

Question 17

Euchromatin

Answer 17

• the parts of the DNA that are actively transcribed

- a loosely packed form, contains areas of DNA that are undergoing active gene transcription

Question 18

Heterochromatin

Answer 18

• DNA that is NOT actively transcribed

- mostly made up of highly condensed DNA

Question 19

Histone

Answer 19

One of several families of proteins around which DNA is wrapped during compaction

Question 20

Chromatin

Answer 20

The combination of DNA and proteins that makes up the chromosomes

Question 21

Nucleosome

Answer 21

• The complex of DNA coiled around the eight core histone subunits: two subunits each of the histones H2A, H2B, H3, and H4; forms bead-like, repeated units in the chromosomes of eukaryotic cells.
• A nucleosome is made up of eight histone proteins. There are two Histone 2A’s (H2A), two Histone 2B, two H3s’ and H4. Histone H1 hold it all together from outside the nucleosome.

Question 22

Centrosome

Answer 22

Organizes the microtubules of the spindle during mitosis in animals.

Question 23

Describe the levels of DNA packaging within the cell (levels of organization of a chromosome)

Answer 23

• The nucleosome is the start of DNA folding and packaging inside the cell
• The next level of packaging is the 30nm fiber. Ultimately, the DNA can be fully condensed
• Condensed chromosomes are only found in cells that are going through cell division.

Question 24

Explain why lipids do not dissolve in water, but sugars do

Answer 24

• Water molecules are polar, which means the oxygen side of the molecule is more negative, and the hydrogen side is more positive.
• Lipids are non polar, which means that one side is not more negative than the other.
• no nonpolar substances dissolve in polar liquids
• Sugars are polar

Question 25

Describe/draw the structure of a biological membrane

Answer 25

* Biological membranes contain both a lipid and a protein component. * While there is a diversity of proteins present in the bilayer – many of the proteins function as transport proteins

Question 26

Describe the various uses of carbohydrates by cells

Answer 26

Energy Storage Structural Support Cell-to-Cell Communication

Question 27

Energy Storage

Answer 27

- starch used in plant cells | - glycogen used in animal cells

Question 28

Structural Support

Answer 28

- cellulose used in cell walls of plants and algae | - peptidoglycan used in cell walls of bacteria

Question 29

Cell to Cell Communication

Answer 29

Attached to proteins and lipids in plasma membrane of cells

Question 30

Memorize examples of molecules that can easily cross a membrane and those that cannot

Answer 30

CAN • small • nonpolar • hydrophobic ``` CANNOT • charged ions • large • proteins • sugars ```

Question 31

Fluid mosaic

Answer 31

* Being made of many separate and distinct components not bonded to each other so as to retain fluid properties; the currently accepted model of cell membrane structure. * Biological membranes have been described as Fluid Mosaics

Question 32

Intergral Membrane Protein

Answer 32

• A protein that is permanently attached to a membrane

Question 33

Peripheral membrane protein

Answer 33

• A membrane protein associated with either the inside or the outside of the membrane; it is anchored to the surface of the membrane but is not embedded within the membrane

Question 34

Glycoprotein

Answer 34

• A protein with carbohydrate modifications; can be secreted from the cell or embedded in the membrane; interactions between glycoproteins on adjacent cells permit cell-cell communication.

Question 35

Diffusion

Answer 35

* Movement of materials from areas of generally higher concentrations to areas of generally lower concentrations; requires no input of energy. * The story of membrane transport is the story of how molecules (solutes) that are suspended in water (the solvent) move across phospholipid bilayers. * Net movement by diffusion is always from high to low.

Question 36

Concentration gradient

Answer 36

* A difference in the concentration of a substance between two different areas, such as the two sides of a selectively permeable membrane. * The state of having different amounts of a solute molecule on one side of a membrane compared to the other

Question 37

Osmosis

Answer 37

• The diffusion of water through a selectively permeable membrane.

Question 38

Solvent

Answer 38

• The solution that is doing the dissolving.

Question 39

Solute

Answer 39

• The “stuff” (molecules) dissolved in a solution

Question 40

Pump protein

Answer 40

* A kind of protein that is capable of pumping out compounds that could pose a threat to the cell * Use ATP energy to change conformation - carrying solute molecules across the bilayer * Moves molecules UP a concentration gradient (against entropy).

Question 41

Channel protein

Answer 41

• Tunnel-like protein structures in cell membranes through which molecules or ions can move; present on both the cell membrane and intracellular organelles such as mitochondria and the endoplasmic reticulum.

Question 42

Carrier protein

Answer 42

* Bind to their solute molecule – like a substrate – and undergo a conformation change that results in the transport of the solute across the membrane. * Work like enzymes * Binding to a specific substrate molecule * Undergoes a conformational change • Moves the molecule DOWN the concentration gradient

Question 43

Connect the idea of energy with concentration gradients

Answer 43

* A concentration gradient is a representative of energy storage. * ATP the energy currency of the cell will require this concentration gradient for its formation. * Higher the concentration gradient the higher will be the stored energy