Chapter 2 DNA, RNA, and Proteins Review

Study Notes

Genes, the fundamental units of inheritance, are constructed of DNA sequences and are positioned on chromosomes.
Each nucleotide, a DNA subunit, is made up of one deoxyribose, a phosphate molecule, and one of four nitrogenous bases. The physical form of DNA is a double helix. Nitrogenous bases in each strand pair up: thymine with adenine and guanine with cytosine.
DNA's four bases encode for amino acids, protein building blocks. Amino acids are specified by triplet sets of nitrogenous bases called codons. Several codons represent the same amino acid.
DNA replication is based on complementary base pairing. A single DNA strand acts as a template for creating a new strand. DNA polymerase, the primary enzyme, adds bases and performs proofreading functions.
Mutations are alterations of genetic material resulting from base pair substitutions or frameshift mutations. Mutagens are substances causing mutations.
Transcription and translation, processes specifying proteins using DNA, involve RNA. RNA shares similarities to DNA but is single-stranded, has a ribose sugar molecule, and uracil as one nitrogenous base instead of thymine.
Transcription is the process of creating RNA from a DNA template, forming messenger RNA (mRNA). Much of the RNA sequence is spliced before mRNA leaves the nucleus.
Translation is the process of RNA guiding protein synthesis in ribosomes. Ribosomes consist of proteins and ribosomal RNA.
Human cells consist of diploid somatic cells (46 total chromosomes) and haploid gametes (23 total chromosomes). Humans have 23 pairs of chromosomes, 22 autosomes and 1 sex chromosome pair.
A karyogram displays chromosomes in order based on length and centromere location, representing the individual's chromosome makeup. Chromosome stains can make bands more visible for identification and variation detection.
Approximately 1 in 150 live births have major diagnosable chromosome abnormalities, known leading causes of intellectual disability and miscarriage.
Euploid cells have the normal number of chromosomes. Polyploidy is a condition with cells having some multiple of the normal number of chromosomes, observed in triploidy and tetraploidy, both lethal.
Aneuploidy occurs when a cell doesn't have a multiple of 23 chromosomes.

Description

Test your understanding of genes, DNA, RNA, and proteins with this review quiz on Chapter 2: Heredity at the Molecular Level. Explore the composition of DNA, the structure of nucleotides, and the double helix model.