Biology Exam 4

transcription

The process where the genetic information in DNA is copied into messenger RNA (mRNA) for protein synthesis. The process by which a cell makes an RNA copy of a piece of DNA. This RNA copy, called messenger RNA (mRNA), carries the genetic information needed to make proteins in a cell.

protein

Large, complex molecules made up of amino acids that perform various functions in living organisms. Made by transcription and translation.

DNA

The molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses, consisting of two strands that coil around each other to form a double helix.

RNA

Used for protein synthesis! A nucleic acid that plays a crucial role in coding, decoding, regulation, and expression of genes, and is essential for protein synthesis.

Uracil

A nitrogenous base found in RNA that pairs with adenine and replaces thymine found in DNA.

RNA polymerase

An enzyme that synthesizes RNA from a DNA template during the transcription process.

Transcription factor

Proteins that help regulate the expression of genes by binding to specific DNA sequences. They play a critical role in initiating and regulating the transcription of RNA.

General Transcription Factor

A protein that assists RNA polymerase in binding to the promoter region of a gene to initiate transcription.

Euchromatin

A less condensed form of chromatin that is accessible for transcription and often associated with actively expressed genes.

Heterochromatin

A tightly packed form of chromatin that is typically transcriptionally inactive and often associated with gene silencing.

Histone

A protein that helps package DNA into structural units called nucleosomes, playing a crucial role in chromatin structure and regulation of gene expression.

Chromatin

The complex of DNA and proteins found in the nucleus of eukaryotic cells, which exists in two forms: euchromatin and heterochromatin, influencing gene expression and DNA replication.

Template strand

The DNA strand that serves as a guide for RNA polymerase during transcription, providing the necessary sequence for complementary RNA synthesis.

Sigma factor

A protein needed for the initiation of transcription in bacteria, it binds to RNA polymerase to form a holoenzyme that recognizes and binds to specific promoter regions on the DNA.

Template strand

The strand of DNA that is used as a template for RNA synthesis during transcription, providing the sequence for complementary RNA nucleotides.

Non-template strand

The DNA strand that is not used for RNA synthesis during transcription; it has the same sequence as the RNA transcript, except for thymine being replaced by uracil.

Antiparallel

Referring to the orientation of DNA strands, where one strand runs in the 5' to 3' direction and the complementary strand runs in the 3' to 5' direction.

Complementary base pairing

The matching of nucleotide bases in DNA or RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine, ensuring accurate replication and transcription.

Promoter

A specific DNA sequence located upstream of a gene that provides a binding site for RNA polymerase and initiates transcription.

Intron

Non-coding sequence of DNA that is removed during RNA processing. Introns are found between exons and are not translated into protein.

Exon

A coding sequence of DNA that is retained in the final mRNA after RNA processing. Exons are expressed in the protein synthesis process.

Splicing

The process of removing introns from pre-mRNA and joining exons together to form a mature mRNA molecule.

PolyA tail

A stretch of adenine nucleotides added to the 3' end of mRNA that protects it from degradation and facilitates export from the nucleus.

5’ cap

A modified guanine nucleotide added to the 5' end of mRNA, important for mRNA stability and initiation of translation.

tRNA

Transfer RNA that carries amino acids to the ribosome during protein synthesis, matching anticodons with codons on mRNA.

rRNA

A type of RNA that, together with proteins, makes up the ribosomes, which are the sites of protein synthesis.

codon

A sequence of three nucleotides on mRNA that codes for a specific amino acid or signals the end of translation.

anticodon

A sequence of three nucleotides in transfer RNA that pairs with a complementary codon in messenger RNA during protein synthesis.

What are the 6 properties of the genetic code?

Triplet, degenerate/redundant, non-overlapping, punctuated, unambiguous, and universal

Triplet

A set of three nucleotides in DNA or RNA that codes for an amino acid or stops signal in protein synthesis.

Degenerate/redundant

Refers to the genetic code's property where multiple codons can encode the same amino acid.

Non-overlapping

The genetic code's property where each nucleotide is part of only one codon, ensuring distinct and separate codons.

Punctuated

Refers to the genetic code's organization where sequences are clearly defined and separated by non-coding regions, allowing for distinct reading frames.

Unambigous

The characteristic of the genetic code whereby each codon specifies only one amino acid, eliminating confusion in translation.

Universal

The property of the genetic code that indicates it is the same across all known life forms, suggesting a common evolutionary origin.

Genetic code

The set of rules that define how sequences of nucleotides in DNA and RNA are translated into the corresponding amino acid sequences in proteins. It comprises codons and is fundamental to cellular function and heredity.

Release factor

A protein that binds to the ribosome during translation termination, triggering the release of the newly synthesized polypeptide chain from the tRNA.

Silent point mutation

A type of point mutation where a change in a DNA sequence does not alter the resulting amino acid sequence of the protein, due to the redundancy of the genetic code

Conservative missense point mutation

A type of point mutation where a single nucleotide change results in a codon that codes for a different amino acid, but the substituted amino acid has similar properties to the original, leading to a potentially minimal impact on protein function

Non-conservative missense point mutation

a type of mutation where a single nucleotide change results in a different amino acid being encoded. New amino acid properties are significantly different then what it was supposed to be. Can cause a change in protein function.

Nonsense point mutation

A type of point mutation that results in a premature stop codon in the amino acid sequence, leading to a truncated/shortened protein that is usually nonfunctional.

Frameshift point mutation

Occurs when insertions or deletions of nucleotides (not in multiples of three) disrupt the reading frame of a DNA sequence, leading to a completely altered protein sequence downstream of the mutation