Biochem and Unity of Life

Question 1

What three elements make up 98% of atoms in an organism? Explain the occurrence of these elements

Answer 1

Oxygen, Hydrogen and Carbon. Hydrogen and Oxygen are present because of ubiquity of water. Carbon present b/c key atom for biomolecules (ideally polymerizable)

Question 2

List the four classes of biomolecules and their functions.

Answer 2

1. proteins- signal molecules, receptor for signal molecules, enzymes, biological catalyst (Versatile)
2. lipids- energy source, barrier
3. Carbohydrates-energy source, store information
4. Nucleic acids-store bio info in cells, encode genetic information

Question 3

What dictates higher order structures of proteins?

Answer 3

Primary structure (sequence of amino acids)

Question 4

What is the main function of nucleic acids? what are the building blocks of nucleic acids?

Answer 4

Information molecules of cell (Store genetic info). Nucleotides are the building blocks of amino acids.

Question 5

Compare and contrast the 2 different types of nucleic acids.

Answer 5

1. DNA (Deoxyribonucleic acid)- double helix of polymers made from deoxyribose sugar, phosphate, and 4 bases, (A , T, G, C; A pairs with T and G pairs w/ C)
2. RNA (Ribonucleic acid)- single stranded polymer made from ribose sugar, phosphate and 4 bases, (A, U G, C). in place of T from DNA, RNA uses U.

Question 6

What is ATP? What does it stand for?

Answer 6

ATP- source of energy. ATP stands for adenosine triphosphate. ATP stores energy for cell to do work. IT also useful for driving coupling hydrolysis reactions in a favorable direction.

Question 7

Describe the different features of DNA Double helix and how they’re linked.

Answer 7

Backbone of double helix is covalently linked by phosphodiester linkages. The bases are hydrogen bonded together (G with C ; A with T).

Question 8

Differentiate between the covalent and noncovalent bond strengths in DNA strand

Answer 8

Covalent bonds are strong, and need enzymes to break the chain. Meanwhile the bases held by h-bonds which are noncovalent are weak bonds, easier to reverse.

Question 9

What are the properties and function of lipids?

Answer 9

Lipids are storage forms for fuel and serve as a barrier. They have hydrophobic and hydrophilic properties. Hence they form barriers called membranes that allow for compartmentalization of cell. Lipids are also fuel and signal molecules. Amphiphatic (one side hydrophillic (head) and another hydrophobic (tail)

Question 10

List the main function of Carbohydrates and provide examples.

Answer 10

Carbs are FUEL, INFORMATION, and signal molecules (cell-cell interaction). Glucose is a common carbohydrate. Glucose stored in animals as glycogen and can be used to produce energy aerobically or anaerobically.

Question 11

What is the central dogma?

Answer 11

states that information flows from DNA to RNA to protein. It describes how DNA is replicated and then translated into RNA, which eventually forms proteins.

Question 12

Which enzyme replicates DNA?

Answer 12

DNA polymerases

Question 13

What nucleic acid structure contain all of the heritable information (genome) ?

Answer 13

DNA (type of nucleic acid)

Question 14

What is the function of RNA polymerase? Why is this selective process important?

Answer 14

it catalyzes transcription which is process of copying DNA information into RNA. Selective transcription of the genome will determine function of cell or tissue.

Question 15

What happens during translation? Where does translation occur?

Answer 15

Translation will convert the nucleic acid sequence information in mRNA into protein sequence info (info from mRNA will convert into amino acid sequence forming protein). Translation occurs on ribosomes.

Question 16

What is a membrane? do eukaryotes have membranes? Prokaryotes?

Answer 16

A membrane is a lipid bilayer (hydrophilic head, hydrophobic tail). Eukaryotes have membrane-enclosed compartments in cell (lipid bilayer forms organelles). Prokaryotes DO NOT have intracellular membranes (only have nuclear envelope, content attached to PM).

Question 17

Why would nature create a membrane that is essentially impermeable to most substances?

Answer 17

For selectivity and retention. Ex: Insulin secretion. Insulin very selective about transporting glucose out of cell.

Question 18

What kind of structures are inserted into membrane (lipid bilayer) for selective permeability?

Answer 18

integral proteins that go through membrane, transporters (transport glucose, Na, Ca), and channels.

Question 19

distinguish between features of prokaryotic cell vs. eukaryotic cell

Answer 19

Prokaryotes- have nucleoid, plasma membrane, cell wall and no membrane organelles. Long bean shape
Eukaryotes- nucleus, PM, membrane bound organelles(ER, golgi, lysosome, mitochondria, secretory vesicles). ghost like shape.

Question 20

What is cytoplasm? how is it organized.

Answer 20

Cytoplasm is the gel- like substance of cell that is surrounded by plasma membrane , but not enclosed by intracellular membranes. Cytoplasm is organized by set of structural filaments called cytoskeleton

Question 21

why is compartmentalization important? what structure is the information center of the cell?

Answer 21

important since biochemical functions are sequestered in the cellular compartments. Nucleus is information center of cell (genome to replicate DNA, Transcribe for RNA).

Question 22

What structure is the primary site of ATP generation in eukaryotic cells? What structure is the major site of photosynthesis? Where are they found?

Answer 22

Mitochondria- site of ATP generation

Chloroplasts- site of photosynthesis; found in plants

Question 23

What is the function of ER? what are the two types of ER and their specific roles?

Answer 23

Endoplasmic reticulum is a series of membranous sacs in the cytoplasm that process and sort proteins, and exchange material within environment.
Two types of ER:
1. Rough ER- has ribosomes that allows for protein processing (making and transporting), bind mRNA.
2. Smooth ER- has NO ribosomes, and plays a variety of biochemical roles.
ER process chemical like ethanol that is ingested.

Question 24

What is the Golgi complex and its function

Answer 24

series of stacked membranes that play in a role of protein sorting. also have carbohydrates attached to proteins in the Golgi complex. These proteins are shuttled from rough ER to Golgi through secretory vesicles.

Question 25

compare and contrast exocytosis and endocytosis. What is an endosome?

Answer 25

Exocytosis- process of how secretory granules secrete biomolecules out of cell (vesicle fuse with PM to expel contents) . ex: neurotransmitters
Endocytosis- bring crucial biomolecules into cell, through receptor-mediated process (target molecules, bind to protein receptor and form vesicles) ex: cholesterol, Iron, viruses and nutrients enter
endosome- structure formed when plasma membrane invaginates and buds off.

Question 26

What kind of process allows for large amount of material to enter the cell? is this a form of endocytosis or exocytosis?

Answer 26

phagocytosis (cell eating) engulfing allows for large materials to enter cell. This is a form of endocytosis.

Question 27

what is the main function of lysosomes?

Answer 27

lysosomes contain a variety of digestive enzymes. They degrade large polymers to its precursors. Lysosome also fuse with endosomes to digest material brought into cell.

Question 28

explain the physical nature of membranes in terms of what and how they compartmentalize structures of the cell.

Answer 28

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