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Reproduction of Organisms
Chapter 10 and 11.4
Reproduction of Organisms
1.
Asexual Reproduction—formation
of offspring from a single parent
2. Forms of Asexual Reproduction



Budding—A form of mitosis used by Hydra,
Jellyfish, Sea Anemones, Yeast and some
Fungi
Spores—haploid reproductive cells
produced by plants during meiosis (making
sex cells)—grow to haploid organisms (ex:
mosses, fungi, ferns)
 Haploid=a cell that has only one
chromosome of each pair—half as many
chromosomes as the parent organism
(n)
Binary Fission—similar to mitosis-cell splits
into two new cells of equal size.
Reproduction of Organisms
3.
Sexual Reproduction
a. 2 haploid gametes (sex cells) unite
to form a zygote (fertilized egg)
b. Animals—almost all multicellular
animals exist as Diploid organisms.
 Diploid= a cell that contains both
chromosomes of a pair. (2n)
c. Plants—most plants have a haploid
and diploid form during their life
cycle.
MITOSIS
Mitosis—cell reproduction in which two identical cells
are made from one cell
 All living things start life as a single cell
 All body growth and repair beyond this first cell
happens through a process called mitosis.
 Chromosomes (contain genes made of DNA) are
duplicated for each new cell
 This process takes from 30 minutes to several
hours and occurs continuously in most organisms
 An exact duplicate of the original cell is made
(much like duplicating or photocopying a piece of
paper)
4. Steps of Mitosis
Interphase
a. Cells not dividing
b. Performs all life
functions
(respiration and
protein synthesis)
c.
Late interphase
(DNA replicates and
the chromosomes
double—looks like
grainy mass in
nucleus)
Steps of Mitosis
Prophase
a. Cell gets ready to separate
nuclear material
b. Distinct rodlike pairs of
chromosomes (chromatids
with centromeres) become
visible
c. Nucleolus and nucleus
breakdown and disappear
d. The centrioles (in animals)
move to opposite ends of the
cell, making spindle fibers
Steps of Mitosis
Metaphase
 Spindle fibers
attached to the
chromosomes
allow all
chromosomes to
line up at the
center of the cell.
Steps of Mitosis
Anaphase
 The original
chromosomes and
their copies are
guided to the
opposite ends of
the cells. Division
of the cytoplasm
begins.
Steps of Mitosis
Telophase
 The cell
membrane begins
to pinch in the
middle as the
fibers begin to
disappear. The
nuclear
membrane and
nucleolus
reappear.
Steps of Mitosis
Two new cells have formed. Both cells
have the same number of
chromosomes as the original.
MEIOSIS
Meiosis is cell division in which 4 daughter
cells with half the number of
chromosomes are formed.
 Meiosis results in egg and sperm cells
(sex cells—gametes) in plants and
animals and spores in some plant cells.
 Meiosis is very much like mitosis except
the cell divides twice resulting in haploid
daughter cells (they have half as much
genetic material as the parent cell)