Download Notes 12 The M Stage Division of Genetic Material

General Biology/Fletcher
Notes #12 Cell Reproduction – The M Stage: Division of the
Genetic Material
 In almost every cell are long molecules that hold _____________ _______________
 This information tells the cell how to grow, develop and _____________
 These long ______________ are called DNA, a type of ____________ ___________
 ___________________ are long strands of DNA wrapped around proteins
 _____________, sections of DNA that hold genetic information, are found in
chromosomes
 In most organisms’ cells ___________________ exist as pairs; each pair has the
same genes – in many instances the paired genes are exactly alike, but in some
instances there are ____________ differences between the genes; paired
chromosomes are called ___________________ chromosomes
 Every _________________ has a characteristic number of chromosomes
 Humans, for example, have _______ chromosomes in each of their body cells
 There are ____ homologous pairs in humans
 Almost every ___________ cell in an organism has the _____________ genetic
information, stored in paired, ______________________ chromosomes
 Two ______________ body cells therefore have the same genetic information,
and they each have the same genetic information as the ______________ cell
 Different types of cells in an organism grow and ____________ differently by
_________________ different parts of the genetic information
 _________________, on the other hand, have only ________ of the genetic
information as the parent cell, and the information in one gamete will differ
somewhat from the information found in another gamete made by the same organism;
these cells have only 1 of each _______________ pair of chromosomes
 An important part of ______________ ___________________ is the process that
insures that daughter cells receive from the parent cell the genetic information (DNA)
that they need
 The process that does this that leads to the production of ____________
__________ is different (but similar) from the process that leads to the
production of _________________
Production of body cells
 Several things must happen so that each daughter cell has the same genetic
information
1. A _______________ of the cell’s DNA has to be made
 Genetic copies are made during the ____ stage of the ________ ___________
 Paired copies are called ________________ __________________
OVER
2. The genetic copies must be separated to either side of the parent cell prior to
division of the parent cell
 When producing body cells genetic copies are separated during the ______
stage of the cell cycle in a process called _________________
 Mitosis - _______________________________________________________
_______________________________________________________________
_________________________________________
Production of gametes
 Many organisms _____________________ by uniting special cells, called gametes
 This process is called __________________; the method of reproduction that
involves joining gametes is called ________________ reproduction
 During fertilization the genetic information of one cell is joined with the genetic
information of another cell to create a new single cell, called a___________________
 The zygote has _______________ as much genetic information as each gamete,
and gametes have ______of the genetic information and ½ of the chromosome
_________________ of the zygote (and all later body cells)
 Gametes are produced from body cells; The process that leads to the production of
daughter cell gametes with ½ of the chromosome number as the parent body cells
involves several steps
1. The genetic material of the parent cell is _____________ during the S stage of the
cell cycle so the parent cell has 2 copies of its DNA
2. _________ rounds of chromosome separation and cell division
 The first round of chromosome separation and cell division produces two
daughter cells with the same number of chromosomes as the body cells
 The second round of chromosome separation and cell division follows,
resulting in _____________ daughter cells, each with ½ of the chromosome
number as the body cells
 Example: production of human gametes and fertilization
Body cells = 46 chromosomes
After S stage = ____________ chromosomes
After first round of chromosome separation and cell division = _____ chromosomes
After second round of chromosome separation and cell division = _____ chromosomes
Gametes (23 chromosomes each) combine to create zygote = _____ chromosomes
__________________ - the process wherein homologous chromosomes and sister
chromatids are separated so that when cell division occurs (__________________) each
gamete has ½ of the number of chromosomes as the original _____________________