Chapter 13 Study guide

For science class

Where does transcription happen, and what is it?

In the nucleus of eukaryotic cells and in the cytoplasm of prokaryotes, the process by which the genetic code from DNA is copied into messenger RNA (mRNA), which then directs protein synthesis.

where does translation occur, and what is it?

Translation occurs in the cytoplasm of both eukaryotic and prokaryotic cells, and it is the process by which messenger RNA (mRNA) is decoded by ribosomes to synthesize proteins.

Base pairs of DNA and RNA

Adenine pairs with thymine (or uracil in RNA), and cytosine pairs with guanine.

What is cell specialization?

The process of translating codons involves using the genetic code to convert the three-nucleotide sequences of mRNA into specific amino acids, which are the building blocks of proteins. This is typically facilitated by ribosomes and transfer RNA (tRNA) in the cytoplasm.

How is cell specialization controlled or regulated?

Cell specialization is controlled by gene expression, which determines which proteins are produced in a cell, leading to specific functions and characteristics.

Molecular biology has a central dogma (teaching). What is it.

The central dogma of molecular biology describes the flow of genetic information from DNA to RNA through transcription, and from RNA to protein through translation. It emphasizes that DNA is transcribed into messenger RNA (mRNA), which is then translated into proteins.

What is a three-stranded nucleotide that calls in an amino acid called?

A transfer RNA (tRNA).

How are proteins assembled?

Proteins are assembled through the processes of transcription and translation, where messenger RNA (mRNA) is synthesized from a DNA template and then read by ribosomes to link amino acids together into polypeptide chains, forming proteins.

What are promoters, and what role do they play in transcribing DNA into RNA?

Promoters are specific DNA sequences located at the start of genes that provide a binding site for RNA polymerase and other transcription factors. They play a crucial role in initiating the transcription of DNA into RNA by determining where transcription begins.

What are some positive effects of mutations?

Immunity to diseases and such.

What is a substitution mutation?

a type of genetic mutation where a single nucleotide base (A, T, C, or G) in a DNA sequence is replaced by a different base.

What is a deletion mutation?

a genetic error where one or more nucleotides (DNA bases) are removed from a DNA sequence.

Describe a homeobox gene?

A highly conserved family of master regulator genes that control the body plan, segmentation, and differentiation of tissues in multicellular organisms during early development.

What are introns?

Non-coding sequences of DNA and RNA found within genes that are removed during the RNA maturation process.

What are exons?

The segments of DNA or RNA that remain in the mature messenger RNA (mRNA) after splicing, where introns are removed.

Where are uracil present?

Ribonucleic acid (RNA).

How do DNA and RNA differ?

Differ primarily in structure, sugar type, and function. DNA is a double-stranded helix storing genetic information with deoxyribose sugar and bases A, T, C, G. RNA is usually single-stranded, uses ribose sugar, replaces Thymine (T) with Uracil (U), and acts to express that information.

What is RNA interference?

A natural cellular process that silences specific genes by degrading messenger RNA (mRNA) or inhibiting its translation, preventing protein production.

Describe the relationship between codons and amino acids.

Codons are three-nucleotide sequences in mRNA that dictate the sequence of amino acids in a protein during translation.

What is a mutagen?

A physical or chemical agent that permanently changes an organism's DNA, increasing the frequency of mutations above natural background level.

What is polyploidy?

Condition in which an organism has extra sets of chromosomes.

What are mutations?

Change in the genetic material of a cell.

How many codons are there in the genetic code?

64

Describe RNA.

A vital molecule found in all living cells, acting as a messenger that carries instructions from DNA to produce proteins.

What is an operon?

In prokaryotes, a group of adjacent genes that share a common operator and promoter and are transcribed into a single mRNA.

Give the steps of translation.

Initiation (The Start): Ribosome hooks onto the mRNA at the start signal.

Elongation (The Growth): Amino acids are added one by one to grow the chain.

Termination (The End): The ribosome hits a stop signal and releases the finished protein.

Give the two major types of mutations, and describe how they are alike and different.

Gene Mutation (Small Scale)

A change in the DNA sequence of a single gene.

Scale: Affects one specific protein

Chromosomal Mutation (Large Scale)

A change in the structure or number of entire chromosomes.

Scale: Affects hundreds or thousands of genes at once.

Give the name and function of each type of RNA.

The Job: The Message.

Function: It carries the genetic "recipe" from the DNA to the ribosome.

tRNA (Transfer)

The Job: The Truck.

Function: It "transfers" or delivers the correct amino acids to the ribosome to build the protein.

rRNA (Ribosomal)

The Job: The Ribosome.

Function: It forms the physical structure of the ribosome—the "workbench" where the protein is made.