Chapter 4 DNA structure and gene expression Term exam

Structure of DNA

Double stranded and twists to form a helix

Parts of a nucleotide

Pentose (5-carbon) sugar, a phosphate group, and a nitrogenous base

Purine Bases

Adenine and Guanine

Purimidines

Thymine and Cytosine

Difference between Purine and Pyrimidines

Double-ring structure, and single-ring structure

Which bases are complementary in DNA

A + T and G+C

Antiparallel DNA strands

Strands run in the opposite direction

What is the difference in the way leading and lagging strands are replicated

One is replicated continuously, while the other is replicated in short segments called Okazaki fragments.

What happens during transcription

The process in which a portion of DNA serves as a template for mRNA formation ,takes place in the nucleus.

Which enzyme is involved in transcription

RNA Polymerase

Function of mRNA

carries genetic instructions from DNA in a cell's nucleus to the cytoplasm so ribosomes can build proteins

Function of tRNA

Acts as a molecular adaptor or bridge during protein synthesis connecting the genetic code in messenger RNA to the specific amino acid sequence of a growing protein

Function of rRNA

Ribosomal RNA is the core molecular building block of ribosomes, the machinery that manufacture proteins in all living cells.

Initiation stage of translation

First step of protein synthesis in which all translation components are brought together by initiation factor proteins.

Elongation

Second step in protein synthesis, in which a polypeptide increases in length one amino acid at a time.

When a newly-synthesized polypeptide leaves a ribosome, is there anything else that must occur before it is a fully functional protein?

Protein folding into its stable three-dimensional shape.

What is a metabolic Pathway

A series of chemical reactions in a cell where the product of one reaction becomes the substrate for the next reaction, each step is controlled by a specific enzyme.