Biology

DNA and Nucleotide

DNA = the carrier of genetic information.

Nucleotide = one of the building blocks of DNA.

Chromosome

A thread-like structure in all living cells that consist of a single molecule of DNA bonded to various proteins and contains genetic information.

Sister chromatids

Each of the two thread-like strands into which a chromosome divides long ways during cell division. They are held together by a centromere

Gene, Allele, Locus

Allele = Different forms of a gene.

Gene = the fundamental physical and functional unit of heredity.

Locus/loci = The location of a gene on a given chromosome

Histones, Nucleosomes

Histone = Protein DNA wraps around.

Nucleosome = DNA wrapped around histones.

Function = Packages DNA into chromosomes

Homologous and Non-homologous chromosomes

Homologous = Same genes, Same loci, Same size, and One from each parent

Non-homologous = Different genes, and Different sizes

Diploid and Haploid

Diploid:Definition = Contains two sets of chromosomes/2n

Haploid: Definition = Contains one set of chromosomes/n

Homozygous genotype and heterozygous genotype

Homozygous genotype: Two identical alleles. e.g. AA or aa

Heterozygous genotype: Two different alleles. e.g Aa or aA

RNA nucleotide

Bases: Adenine, Uracil, Cytosine, and Guanine

Difference from DNA: Contains ribose sugar. Uses uracil instead of thymine.

RNA = Ribonucleicacid

Protein and Amino acids

Amino acid: Building block of proteins.

Protein: Folded chain of amino acids.

Functions: Enzymes, Hormones, and Antibodies

Proteins are made during transcription and translation

Transcription

Step 1: RNA polymerase binds promoter.

Step 2: DNA unzips.

Step 3: Complementary pre-mRNA produced.

Occurs in nucleus.

RNA processing

Steps: Remove introns. Join exons. Add 5' cap. Add Poly-A tail. Leaves nucleus as mature mRNA.

Translation

Step 1: mRNA attaches to ribosome.

Step 2: tRNA anticodons pair with mRNA codons.

Step 3: Ribosome joins amino acids with peptide bonds to build a polypeptide until a stop codon is reached.

Occurs in cytoplasm.