Definitions and Structure of DNA Flashcards
Why do cells divide?
Growth, development, repair, and formation of gametes
Cell Division
When a cell divides, its DNA is copied and distributed
DNA Function
Stores info that tells cells which proteins to make and when to make them
Genes
Thousands of units of info that code for proteins (found in DNA)
Chromosomes
DNA coils to form a chromosome - occurs when cell is about to divide
Chromatids
Two exact copies of the DNA that makes up each chromosome - attached at centromere and separate during cell division (one placed into each cell, ensuring they are exactly the same)
Chromosomes in Humans
46 chromosomes consisting of 23 pairs of homologous chromosomes (means they are similar in shape, size, and genetic compound - each homologue comes from each parent)
Somatic Cells
Any cells except sex cells (any other body cells) that have 46 chromosomes (two sets of 23)
Reproductive Cells
Egg and sperm cells (sex cells) that have 23 chromosomes (one set of 23)
Diploid Cells
Cells that contain two sets of chromosomes (denoted as 2n = 46 in humans) - somatic cells are diploid cells
Haploid Cells
Cells that contain one set of chromosomes (denoted as n = 23 in humans) - sex cells are haploid cells
DNA Structure
Deoxyribonucleic acid –> type of nucleic acid (complex organic substance that holds info) that is a double helix found in nucleus and is the main component of genes
Nucleotide
- Deoxyribose sugar
- Phosphate group
- Nitrogenous base
Nitrogenous Bases
Adenine, guanine, cytosine, thymine –> AT2 (adenine + thymine with 2 hydrogen bonds) and CG3 (cytosine + guanine with 3 hydrogen bonds)
Pyrimidines: 1 ring structure (cytosine and thymine)
Purines: 2 ring structure (adenine and guanine)
*Order of bases determines individuality of nucleic acid
Gametes
Sex cells (egg and sperm cells)
