Transcript Reproduction - Mexico Central School District

 The life process by which an
organism produces new
individuals of the same kind.
 This is essential for the survival
of the species
 Asexual Reproduction
one parent and
 Involves ________
results in one or more offspring
identical to
that are genetically _________
that parent.
 Cells reproduce by Mitosis
 A process where a cell divides and creates
two daughter cells which are identical to
the parent

Cell Division happens by series of phases
▪ Interphase, prophase,
metaphase,anaphase, and telophase
(cytokinesis)
▪ I.P.M.A.T.(C).
I.P.M.A.T.C.
interphase
prophase
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase
chromosomes in cell
DNA in chromosomes
cell
nucleus
4 single-stranded chromosomes
duplicated chromosomes
duplicated
chromosomes
4 double-stranded chromosomes
cell
nucleus

Stage 1: cell copies DNA
Copy DNA!
DNA
cell
nucleus
INTERPHASE

Stage 2: DNA winds into chromosomes
 Nuclear membrane disappears
 Spindle Fibers/ Centrioles appear
duplicated chromosomes
Wind up!
cell
nucleus
PROPHASE
double-stranded
human chromosomes
ready for mitosis

Stage 3: Chromosomes line up in middle
 attached to protein “cables” that will help
them move
Line up!
duplicated chromosomes
lined up in middle of cell
METAPHASE

Stage 4: Chromosomes separate
 start moving to opposite ends
Separate!
chromosomes split &
move to opposite ends
ANAPHASE

Stage 5: Cell starts to divide
 Two nuclei
 Chromosomes unwind
Divide!
TELOPHASE

Stage 6: DNA unwinds again
 cells separate completely (cleavage furrow)
 now they can do their every day jobs
Bye Bye!
CYTOKINESIS
Biology is the only subject in
which multiplication is the
same thing as division…
Binary Fission
 The cell splits
into two
identical cells,
each containing
an exact copy of
the original cell's
DNA.
Nucleus and Cytoplasm divide
EQUALLY!
Buddingwhere the daughter cell grows out of the
parent and gradually increases in size.
Yeast cells
Hydra
Nucleus divides equally
Cytoplasm divides unequally
Spores




Reproductive cell that contains a nucleus
and a small amount of cytoplasm
Spores are highly resistant to heat
Spores are capable of growing into a new
organism when conditions allow
Produced by bread mold, mushrooms,
mosses and ferns
Regeneration
 Development of a new organism from part of a
parent
 Whole organisms are produced – Starfish!
 Replacement of lost body part
Vegetative Propagation
 Part of a plant (root, stem, leaves) grows into a
new plant
 Seedless fruits & vegetables
 Commonly used by farmers = quick, easy &
successful!

Offspring receive half of their genes from
one parent and half from the other parent

The genes are carried on chromosomes in
sex cells known as gametes

Male gamete is the sperm cell

Female gamete is the ovum (egg)

Joining of 2 sex cells (egg & sperm)

Do we make egg & sperm by mitosis?
No!
What if we did, then….
46
egg
+
46
92
sperm
zygote
Doesn’t work!

Gametes are formed by Meiosis
Meiosis (reduction division)
 In series of divisions the number of
chromosomes is reduced by half

46 chromosomes to 23 chromosomes
 half the number of chromosomes
23
46
meiosis
46
diploid
egg
23
sperm
haploid
 Fertilization
 Two gametes (Ovum and Sperm) join
to create an offspring
 Variation
 Each offspring gets a unique
combination of genes, therefore they
are not identical to their parents or
siblings.
Meiosis (reduction division)
 Spermatogenesis: Creates 4 sperm cells
 Oogenesis: Creates 1 ovum and 3 polar bodies
meiosis  fertilization  mitosis + development
gametes
46
23
meiosis
23
egg
23
46
23
zygote
fertilization
sperm
46
46 46
46 46 46
4646 46
mitosis
&
mitosis
development
Meiosis to make
gametes
 sperm & egg
Mitosis to make
copies of cells
 growth
 repair
 Development
 replacement

Consistency over time
 meiosis keeps chromosome number same from
generation to generation
from Mom
Mom
Dad
offspring
from Dad
We’re
mixing things
up here!

Change over time
 meiosis introduces genetic variation
▪ gametes of offspring do not have
same genes as gametes from parents
▪ new combinations of traits
from Dad
variation
from Mom
offspring
new gametes made by offspring
Crossing Over – Trading DNA!

During prophase 1, sister
chromatids intertwine
 homologous pairs swap
pieces of chromosome
▪ DNA breaks & re-attaches
tetrad
prophase 1
Sexual reproduction allows us to maintain both genetic
similarity & differences.
Jonas
Brothers
Baldwin brothers
Martin & Charlie Sheen, Emilio Estevez
 The nucleus is taken from parent
with a complete set of genetic
information
 Injected into an egg cell which has
had its nucleus removed
 The egg is implanted in a
surrogate mother
 Result is an organism which is
100% genetically identical to
parent
Many more to come… Too many to list…