chapter 12 bio

RNA vs DNA (similarities & differences)

Similarities: Both carry genetic information and are made of nucleotides.

Differences: DNA is double-stranded and stays in the nucleus; RNA is single-stranded and can leave the nucleus. RNA uses uracil instead of thymine.

Types of RNA & functions

mRNA: Carries instructions to make proteins

tRNA: Brings amino acids to ribosomes

rRNA: Makes up ribosomes

What is transcription

Transcription is when DNA is copied into RNA.

RNA polymerase binds to the promoter and makes the RNA strand.

what are introns

non-coding regions of DNA

what are exons

coding regions of DNA

what happens to introns and exons during splicing

During splicing, introns are cut out and exons are joined.

what is a codon

3 mRNA bases that code for an amino acid

What is the genetic code

the set of rules that determines how a nucleotide sequence is converted into the amino acid sequence of a protein

What is a polypeptide

chain of amino acids

What is a start codon

AUG (methionine)

what is a stop codon

UAA, UAG, UGA

How does translation work?

• - mRNA leaves the nucleus and finds a ribosome

  - tRNA, carrying an amino acid, matches its anticodon to the codon on the mRNA

  - this continues and an amino acid chain is made

  - when the mRNA reaches a stop codon, the matching tRNA releases the protein and synthesis is complete

What is molecular biology

Study of DNA, RNA, and proteins and how they control cell functions.

Why do cells need to regulate their genes

Cells regulate their genes to control which proteins are made, allowing them to save energy, specialize, respond to their environment, and maintain balance.

what is an operon

a group of genes that are regulated together

How does gene regulation work in the lac operon?

The lac operon is regulated by a repressor that binds to the operator and blocks transcription when lactose is absent; when lactose is present, it inactivates the repressor, allowing RNA polymerase to transcribe genes needed to break down lactose.

Eukaryotic vs prokaryotic gene regulation

Prokaryotes: Use operons

Eukaryotes: Use transcription factors, enhancers, and chromatin changes

how are the TATA box, enhancers, transcription factors involved in eukaryotic gene regulation

The TATA box helps position RNA polymerase, transcription factors bind to the TATA box to start transcription, and enhancers increase transcription by binding activator proteins that help RNA polymerase bind more efficiently.

What makes cell specialization possible in multicellular organisms

Cell specialization is possible because different cells turn specific genes on or off, allowing them to produce different proteins even though they all contain the same DNA.

What do homeotic genes do?

They control body development and the placement of body parts.

How do environmental factors affect gene expression?

They can turn genes on or off without changing DNA.

How does epigenetics regulate gene expression?

Chemical tags on DNA or histones control whether genes are expressed.

What are mutations and the difference between point and chromosomal mutations?

Mutations are DNA changes; point mutations affect one gene, chromosomal mutations affect many genes.

What are silent, missense, and nonsense mutations?

Silent doesn't change amino acids, missense changes one amino acid, nonsense creates a stop codon.

What are substitution, insertion, and deletion mutations?

Substitution replaces a base; insertion adds a base; deletion removes a base.

What are frameshift mutations?

Insertions or deletions that shift the reading frame.

What are the four types of chromosomal mutations?

deletion, duplication, inversion, translocation

What are mutagens and what do they do?

Mutagens are physical or chemical agents that damage DNA or interfere with DNA replication. They can cause mutations by changing DNA bases, breaking DNA strands, or altering chromosome structure, which may lead to harmful, beneficial, or neutral effects in organisms.

What are the three possible effects of mutations?

beneficial, neutral or harmful

What is polyploidy and how does it affect organisms?

Polyploidy is having extra chromosome sets; common and helpful in plants, rare and harmful in animals.