BIO102 - Cell Biology & Fundamental Processes Flashcards

Question 1

Differentiate between prokaryotic and eukaryotic cells.

Accepted Answer

Prokaryotic cells lack a membrane-bound nucleus and organelles, are generally smaller, and have circular DNA (e.g., bacteria, archaea). Eukaryotic cells have a true nucleus and membrane-bound organelles, are larger, and have linear DNA (e.g., animal, plant, fungi, protists).

Question 2

Describe the key structural components of a prokaryotic cell.

Accepted Answer

Prokaryotic cells typically have a cell wall, cell membrane, cytoplasm, ribosomes, and a nucleoid region containing circular DNA. Some may also have flagella, pili, or a capsule.

Question 3

List the major structural components found in a eukaryotic cell.

Accepted Answer

Eukaryotic cells contain a cell membrane, cytoplasm, ribosomes, a nucleus, mitochondria, endoplasmic reticulum (rough and smooth), Golgi apparatus, lysosomes, and a cytoskeleton. Plant cells also have a cell wall, chloroplasts, and a large central vacuole.

Question 4

What is the primary function of the nucleus in a eukaryotic cell?

Accepted Answer

The nucleus houses the cell's genetic material (DNA) organized into chromosomes, controls gene expression, and regulates cell growth, metabolism, and reproduction. It is enclosed by a double membrane called the nuclear envelope.

Question 5

Describe the structure and function of mitochondria.

Accepted Answer

Mitochondria are double-membraned organelles. The inner membrane is folded into cristae, increasing surface area. They are the 'powerhouses' of the cell, responsible for cellular respiration and generating most of the cell's supply of ATP ($C_6H_{12}O_6 + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{ATP}$).

Question 6

What are chloroplasts, and what is their main role?

Accepted Answer

Chloroplasts are double-membraned organelles found in plant cells and algae. They contain stacks of thylakoids called grana, surrounded by stroma. Their primary role is photosynthesis, converting light energy into chemical energy ($6CO_2 + 6H_2O + 	ext{Light Energy} ightarrow C_6H_{12}O_6 + 6O_2$).

Question 7

Explain the functions of the Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).

Accepted Answer

The RER is studded with ribosomes and is involved in the synthesis, folding, modification, and transport of proteins destined for secretion or insertion into membranes. The SER lacks ribosomes and is involved in lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions.

Question 8

What is the Golgi apparatus, and what does it do?

Accepted Answer

The Golgi apparatus (or Golgi complex/body) is a stack of flattened membrane-bound sacs called cisternae. It modifies, sorts, and packages proteins and lipids synthesized in the ER into vesicles for secretion or delivery to other organelles. It has a _cis_ face (receiving) and a _trans_ face (shipping).

Question 9

Describe the structure and function of lysosomes.

Accepted Answer

Lysosomes are membrane-bound organelles containing hydrolytic enzymes. They function as the cell's 'recycling centers,' breaking down waste materials, cellular debris, and foreign invaders (like bacteria) through phagocytosis and autophagy.

Question 10

What is the cytoskeleton, and what are its three main components?

Accepted Answer

The cytoskeleton is a network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence. Its three main components are:
1.  **Microtubules:** Hollow tubes, involved in cell shape, organelle movement, cilia/flagella.
2.  **Microfilaments (Actin Filaments):** Solid rods, involved in muscle contraction, cell division, cell shape.
3.  **Intermediate Filaments:** Rope-like, provide structural support, anchor organelles.

Question 11

Briefly describe the overall process of glycolysis, including its location.

Accepted Answer

Glycolysis is the first stage of cellular respiration, occurring in the cytoplasm. It involves the breakdown of one molecule of glucose ($C_6H_{12}O_6$) into two molecules of pyruvate ($C_3H_4O_3$). It produces a net gain of 2 ATP and 2 NADH.

Question 12

What are the key inputs and outputs of glycolysis?

Accepted Answer

**Inputs:** 1 Glucose, 2 ATP (for activation), 2 $NAD^+$, 4 ADP + 4 P$_i$
**Outputs:** 2 Pyruvate, 2 Net ATP (4 produced, 2 consumed), 2 NADH, 2 $H_2O$

Question 13

Where does the Krebs cycle (citric acid cycle) take place, and what are its main products?

Accepted Answer

The Krebs cycle occurs in the mitochondrial matrix. For each acetyl-CoA entering the cycle, it produces 3 NADH, 1 $FADH_2$, 1 ATP (or GTP), and releases 2 $CO_2$. Since one glucose yields two acetyl-CoA, these outputs are doubled per glucose molecule.

Question 14

What are the key inputs and outputs of the Krebs cycle (per glucose molecule)?

Accepted Answer

**Inputs:** 2 Acetyl-CoA (from 2 pyruvate), 6 $NAD^+$, 2 $FAD$, 2 ADP + 2 P$_i$ (or GDP + P$_i$)
**Outputs:** 4 $CO_2$, 6 NADH, 2 $FADH_2$, 2 ATP (or 2 GTP)

Question 15

Explain the overall purpose and location of oxidative phosphorylation.

Accepted Answer

Oxidative phosphorylation is the final stage of cellular respiration, occurring on the inner mitochondrial membrane. Its purpose is to generate a large amount of ATP by coupling the oxidation of NADH and $FADH_2$ (electron carriers) with the phosphorylation of ADP, driven by an electrochemical proton gradient.

Question 16

What are the two main components of oxidative phosphorylation?

Accepted Answer

1.  **Electron Transport Chain (ETC):** A series of protein complexes that accept electrons from NADH and $FADH_2$, passing them down a chain and releasing energy to pump protons ($H^+$) into the intermembrane space.
2.  **Chemiosmosis:** The process where protons flow back across the inner mitochondrial membrane through ATP synthase, driving the synthesis of ATP from ADP and P$_i$.

Question 17

What are the inputs and outputs of the light-dependent reactions of photosynthesis?

Accepted Answer

**Inputs:** Light energy, $H_2O$, $NADP^+$, ADP + P$_i$
**Outputs:** $O_2$ (as a byproduct), ATP, NADPH
**Location:** Thylakoid membranes within chloroplasts.

Question 18

Describe the main events occurring during the light-dependent reactions.

Accepted Answer

Light energy is absorbed by chlorophyll in photosystems (PSII and PSI), exciting electrons. These electrons move through an electron transport chain, pumping protons into the thylakoid lumen, creating a gradient. Water is split to replace electrons (releasing $O_2$). The proton gradient drives ATP synthesis via ATP synthase (photophosphorylation), and electrons reduce $NADP^+$ to NADPH.

Question 19

What is the primary purpose of the light-independent reactions (Calvin cycle)?

Accepted Answer

The Calvin cycle uses the ATP and NADPH produced during the light-dependent reactions to fix atmospheric carbon dioxide ($CO_2$) into organic molecules, specifically glucose or other carbohydrates.

Question 20

What are the inputs and outputs of the Calvin cycle (per 3 $CO_2$ molecules fixed)?

Accepted Answer

**Inputs:** 3 $CO_2$, 9 ATP, 6 NADPH
**Outputs:** 1 G3P (glyceraldehyde-3-phosphate, a 3-carbon sugar that can be used to synthesize glucose), 9 ADP + 9 P$_i$, 6 $NADP^+$
**Location:** Stroma of the chloroplast.

Question 21

List the three main phases of the Calvin cycle.

Accepted Answer

1.  **Carbon Fixation:** $CO_2$ is incorporated into an organic molecule (RuBP) by the enzyme RuBisCO.
2.  **Reduction:** The fixed carbon molecule is reduced using ATP and NADPH to form G3P.
3.  **Regeneration:** ATP is used to regenerate RuBP, allowing the cycle to continue.

Question 22

What is the role of ATP synthase in both cellular respiration and photosynthesis?

Accepted Answer

ATP synthase is an enzyme that uses the energy from a proton ($H^+$) gradient to catalyze the synthesis of ATP from ADP and inorganic phosphate ($P_i$). In cellular respiration, this occurs on the inner mitochondrial membrane; in photosynthesis, it occurs on the thylakoid membrane.

Question 23

How do plant cells differ from animal cells in terms of key organelles?

Accepted Answer

Plant cells typically have a rigid cell wall (for structural support), chloroplasts (for photosynthesis), and a large central vacuole (for turgor pressure and storage) that are absent in animal cells. Animal cells have centrioles (involved in cell division) which are generally absent in plant cells.

Question 24

What is the overall chemical equation for cellular respiration?

Accepted Answer

$C_6H_{12}O_6 + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{Energy (ATP + Heat)}$

Question 25

What is the overall chemical equation for photosynthesis?

Accepted Answer

$6CO_2 + 6H_2O + 	ext{Light Energy} ightarrow C_6H_{12}O_6 + 6O_2$

BIO102 - Cell Biology & Fundamental Processes

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