AP Biology Chapter 18 Flashcards

Questions and Answers

What is an operon?

A type of RNA that regulates gene expression

A cell component involved in transcription

A protein that binds to DNA

A piece of DNA consisting of a promoter, operator, and genes for a specific metabolic pathway (correct)

Where does RNA polymerase bind?

promoter

The operator acts as an 'on/off' switch for RNA polymerase binding.

True

What regulates operons?

repressors Signup and view all the answers

In bacteria, how are genes coded compared to eukaryotes?

Genes coded together are transcribed and translated together. Signup and view all the answers

What are the two types of operons?

repressible and inducible Signup and view all the answers

How does a repressible operon function?

When the substance is absent, the repressor is inactive and RNA polymerase can bind. Signup and view all the answers

How does an inducible operon work?

When the substance is present, it binds to the repressor, making it inactive. Signup and view all the answers

A typical human cell expresses about what percentage of its genes at a given time?

20 Signup and view all the answers

What percentage of human DNA codes for proteins?

1.5 Signup and view all the answers

What are control elements?

Segments of noncoding DNA that help regulate transcription. Signup and view all the answers

What do transcription factors do?

They are proteins required for transcription in eukaryotes. Signup and view all the answers

What involves chromatin packing?

Pretranscription control of gene expression. Signup and view all the answers

What is post-transcriptional control?

RNA processing and export, mRNA degradation. Signup and view all the answers

What are miRNAs and how do they regulate gene expression?

Small RNA molecules that bind to complementary mRNA sequences. Signup and view all the answers

What are proto-oncogenes?

Genes that code for proteins stimulating cell cycle and division. Signup and view all the answers

What do tumor suppressor genes do?

Code for proteins that inhibit cell division. Signup and view all the answers

What leads to cell differentiation?

The process of cells becoming specialized in structure and function. Signup and view all the answers

What is induction in terms of gene expression?

Environment around a cell affects it and causes changes in gene expression. Signup and view all the answers

What is determination in cellular biology?

Events that lead to observable differentiation of a cell. Signup and view all the answers

Study Notes

Gene Regulation in Prokaryotes

Operon: DNA segment with a promoter, operator, and genes for a metabolic pathway; found in bacteria.
Promoter: Binding site for RNA polymerase to initiate transcription.
Operator: Functions as an "on/off" switch for RNA polymerase binding.
Operon Regulation: Governed by repressors that attach and detach from the operator, specific to an operon.
Transcription and Translation in Bacteria: Genes are transcribed and translated together, in contrast to eukaryotic individual gene processing.

Types of Operons

Repressible Operon: Normally on; repressor activated by the presence of a substance, blocking RNA polymerase.
Inducible Operon: Normally off; repressor inactivated by a substance, allowing RNA polymerase to bind.

Human Gene Expression

Gene Expression: Approximately 20% of human genes expressed at any given time.
Protein-Coding DNA: Only about 1.5% of human DNA codes for proteins, while the remainder codes for RNA or is non-transcribed.

Eukaryotic Gene Regulation

Coordinately Controlled Genes: May cluster together, with each having its own promoter or shared promoters, subjected to chromatin modifications that affect transcription availability.
Control Elements: Noncoding DNA segments that help regulate transcription by binding proteins, can be near or far from the promoter.

Mechanisms of Gene Regulation

Transcription Factors: Proteins necessary for transcription; some bind to DNA, others to other transcription factors.
Pretranscription Control: Involves chromatin packing, methylation, histone modification, and epigenetic inheritance.
Transcriptional Control Events: Involves binding of transcription factors to enhancers, forming initiation complexes, or blocking by repressors.

Post-Transcriptional and Translational Control

Post-Transcriptional Control: Processes like RNA processing, degradation, and microRNA interference that regulate mRNA stability and translation.
Translational Control: Involves repressor proteins that attach to mRNA UTRs, preventing translation, and regulating factors necessary for initiation.

Post-Translational Control

Post-Translational Modifications: Protein processing, addition of functional groups, transport, and selective degradation mediated by ubiquitin.

Small RNA Molecules

miRNAs: Regulate gene expression by binding complementary mRNA sequences, resulting in degradation or translation blocking.
siRNAs: Small double-stranded RNA molecules that degrade mRNA and modify chromatin.

Developmental Biology

Cell Differentiation: Process leading to specialization in structure and function.
Morphogenesis: Physical processes contributing to the organism's shape.
Cytoplasmic Determinants: RNA and proteins from the mother that unevenly distribute in the egg and influence daughter cell gene expression.
Induction: Environmental signals guiding cell gene expression changes.

Key Genetic Concepts

Determination: Events resulting in observable cell differentiation; irreversible.
MyoD Gene: Master regulatory gene that activates muscle cell transcription.
Pattern Formation: Development of spatial organization guided by determinants and induction signals.

Proto-Oncogenes: Genes that promote cell cycle and division; mutations lead to oncogenes, causing cancer.
Tumor Suppressor Genes: Inhibit cell division; mutations require both alleles to be recessive. p53 gene mutation occurs in over 50% of cancers.
Retroviruses: Viral DNA integrates with host DNA, potentially activating oncogenes or disrupting suppressor genes.

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Description

Explore key terms from AP Biology Chapter 18, focusing on the regulation of gene expression. This set includes definitions and explanations of essential concepts like operons, promoters, and operators, crucial for understanding bacterial gene regulation. Test your knowledge and reinforce your learning with these flashcards.