CR: Cell Reproduction Overview
Cell Reproduction
Cell reproduction is one of the essential characteristics of life. It allows for growth, repair, and the ability to produce offspring.
Every human starts out as a single cell that replicates until developing into a multicellular human with specialized groups of cells. Some of those specialized cells can divide to produce gametes that may contribute to another offspring!
Module Lessons Preview
In this module, we will study the following topics:
Module Key Terms
Key Terms
- Cell Division: the process of creating two new cells either by the process of mitosis or meiosis, ending with cytokinesis
- Cell Cycle: what occurs during the life of a cell; includes interphase and cell division
- Mitosis: when a cell divides into two identical cells
- Cytokinesis: when the cytoplasm splits into two new cells
- Chromatin: a form of DNA in the nucleus that appears as long, disorganized strands
- Chromosomes: a form of tightly coiled shortened and thickened DNA that appears right before DNA replication and mitosis
- Sister Chromatids: the 2 sides of the “X” formed by replicated chromosome and connected by a centromere
- Centromere: connects the two sister chromatids together
- Autosomes: all chromosomes except the sex chromosomes
- Sex Chromosomes: in humans, the 23rd pair of homologous chromosomes determines whether the child is male (XY) or female (XX)
- Homologous Pairs: matching chromosomes that each came from one parent (mother, father); homologs code for different versions of the same gene
- Gene: a section of DNA that codes for a protein/trait
- Alleles: different versions of the same gene
- Tumor: an abnormal mass of tissue caused by uncontrollable cell growth
- Mutation: a change in the DNA sequence
- Spindle Fibers: thin, protein filaments that guide the chromosomes during the process of cell division
- Cell Plate: a structure that eventually becomes the cell wall that forms during cytokinesis
- Cleavage Furrow: a pinched area of the cell that begins cytokinesis; not found in cells with a cell wall
- Meiosis: the reproduction of gametes (sex cells); produces cells with half the number of chromosomes as the original cell
- Diploid Number: the total number of chromosomes found in normal body cells; two matching homologs of each kind
- Haploid Number: ½ the total number of chromosomes found in a normal body cell; one of each kind of homolog
- Tetrad: homologous chromosomes from each parent pair up to form two attached sets of chromatids; “tetra” means 4 for the four chromatids
- Crossing Over: each chromatid may exchange part of itself with its homolog as it crosses over the other during late prophase I or early metaphase I
- Genetic Recombinations: different ways chromosomes can provide variation in the species depending on which chromosomes are inherited and if crossing over occurs
- Gametogenesis: production of gametes by meiosis; two types are oogenesis and spermatogenesis
- Oogenesis: meiosis that produces eggs (ova)
- Ovum: haploid, female reproductive cell; also called an egg
- Spermatogenesis: meiosis that produces sperm
- Sperm: haploid, male reproductive cell
- Somatic Cell: all the body cells (liver, skin, stomach, etc) except the sex cells (gametes)
- Gametes, or Sex Cells: sperm and egg cell