Molecular Biology: Gene Expression and Function

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Questions and Answers

What mechanism primarily drives the differentiation of cells?

Structural changes in the genome

Random gene activation across the genome

Selective gene expression through regulatory factors (correct)

Continuous expression of all genes

Which step of gene regulation is considered the most efficient?

Post-translational modification

Degradation of mRNA

Translation regulation

Transcription regulation (correct)

What role do Oct4, Sox2, and Klf4 play in cellular biology?

They are enzymes involved in DNA replication

They are structural proteins in muscle cells

They are metabolic intermediates in the TCA cycle

They are transcription factors sufficient for reprogramming cells into pluripotent stem cells (correct)

Which of the following technologies is employed to amplify specific DNA sequences?

PCR Signup and view all the answers

Where within the cell does glycolysis occur?

Cytosol Signup and view all the answers

What are the end products of fermentation in yeast?

Ethanol and Carbon Dioxide Signup and view all the answers

Which organelle is primarily responsible for ATP generation through oxidative phosphorylation?

Mitochondria Signup and view all the answers

How do amino acids contribute to energy generation in the TCA cycle?

They can be converted to intermediates that enter the TCA cycle Signup and view all the answers

What enzyme is responsible for synthesizing ATP during oxidative phosphorylation?

ATP synthase Signup and view all the answers

What is the primary role of acetyl-CoA in cellular metabolism?

As a central metabolite in both catabolism and anabolism Signup and view all the answers

In which part of the mitochondria is the proton gradient established?

Inner membrane Signup and view all the answers

How many ATP and NADPH are consumed in each turn of the Calvin cycle?

9 ATP and 6 NADPH Signup and view all the answers

What is the main product of the Calvin cycle?

Glyceraldehyde 3-phosphate (G3P) Signup and view all the answers

Which photosystem occurs first in the light reactions of photosynthesis?

Photosystem II Signup and view all the answers

What is the most abundant phospholipid species in the cell membrane?

Phosphatidylcholine Signup and view all the answers

How do transport proteins function in cell membranes?

By facilitating the movement of substances across membranes Signup and view all the answers

Study Notes

Control of Gene Expression

Different cell types arise from the same genome through selective gene expression.
Transcription is the most common and efficient stage for regulating gene expression.
Regulatory proteins control cell differentiation by activating tissue-specific genes.
Oct4, Sox2, and Klf4 are transcription factors required for reprogramming differentiated cells into pluripotent stem cells (iPS cells).

Analyzing the Structure and Function of Genes

PCR amplifies specific DNA sequences for molecular cloning and diagnostics.
Sanger sequencing determines nucleotide order by using dideoxynucleotides.
Restriction enzymes cut DNA at specific sites to create recombinant plasmids.
Reporter genes are linked to regulatory sequences to monitor gene expression.
GFP is a commonly used reporter gene that fluoresces under certain conditions.

How Cells Obtain Energy from Food

Most ATP is generated in mitochondria through oxidative phosphorylation.
Glycolysis occurs in the cytosol, converting glucose to pyruvate.
Pyruvate is converted to acetyl-CoA in the mitochondrial matrix.
The TCA cycle takes place in the mitochondrial matrix.
During fermentation in muscle cells, pyruvate is reduced to lactate, producing 2 ATP per glucose.
Fermentation in yeast converts pyruvate to ethanol and CO2, also producing 2 ATP per glucose.
Fatty acids are broken down into acetyl-CoA through β-oxidation, which enters the TCA cycle for energy production.
Amino acids can be converted to intermediates that enter the TCA cycle for energy production.

Energy Generation in Mitochondria and Chloroplasts

A proton gradient is generated across the mitochondrial inner membrane during the electron transport chain, driving ATP synthesis.
ATP synthase uses the proton gradient to synthesize ATP during oxidative phosphorylation.
Mitochondria have a double membrane with the inner membrane folded into cristae.
Chloroplasts contain thylakoid membranes (site of light reactions) and stroma (site of the Calvin cycle).
Muscle and sperm cells have more mitochondria because they have high energy demands.
Acetyl-CoA plays a central role in both catabolism (TCA cycle) and anabolism (lipid biosynthesis).
Oxygen is the final electron acceptor in the electron transport chain, allowing for efficient ATP production.
In mitochondria, ATP is directly transported to the cytosol for cellular use.
In chloroplasts, ATP is used within the chloroplast to synthesize carbohydrates.
Photosystem II occurs first, producing O2 and ATP, followed by Photosystem I, which produces NADPH.
The Calvin cycle consumes 9 ATP and 6 NADPH in each turn.
The main product of the Calvin cycle is glyceraldehyde 3-phosphate (G3P), which is used to form glucose and other carbohydrates.

Membrane Structure

Membrane organelles include the nucleus, ER, Golgi apparatus, and mitochondria.
Phosphatidylcholine is the most abundant phospholipid in the cell membrane.
Cholesterol helps modulate membrane fluidity by providing membrane stiffness.
Lipid synthesis occurs in the smooth ER, with enzymes like scramblase and flippase facilitating lipid distribution between membrane leaflets.
Membranes are asymmetric, with different lipid compositions on the inner and outer leaflets.
Membrane proteins include transporters, anchors, receptors, and enzymes, each facilitating specific cellular functions.

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Description

This quiz covers essential concepts of gene expression and its regulation, including key transcription factors and the role of reporter genes. Additionally, it explores methods like PCR and Sanger sequencing that are vital for analyzing genes. Test your understanding of how cells utilize energy to function.