Download Chromosomes

Bellwork
 Quietly
have a set and get out your yeast labs
 Answer
the following questions:
 What
is chromatin?
 What
is the cause of Down syndrome?
 What
are centrioles?
Chapter 8: Cell
Reproduction
8.1 Chromosomes
8.1 Chromosomes
 https://www.youtube.com/watch?v=xUrlreMaUrs
8.1 Chromosomes
Objectives:
I will be able to:

Describe the structure of a chromosome

Identify the differences in structure between prokaryotic
chromosomes and eukaryotic chromosomes

Compare the numbers of chromosomes in different species

Explain the differences between sex chromosomes and
autosomes

Distinguish between diploid and haploid cells
Chromosomes
 Chromosomes
– rod-shaped structures made of
DNA and proteins
How Chromosomes are Formed
 starts
with DNA
 DNA
– genetic information of the cell
How Chromosomes are Formed
 DNA
wrapped around histones
 Histone
– protein that supports shape of chromosomes
How Chromosomes are Formed
 DNA
 Who
wrapped around histones creates chromatin
remembers what chromatin is? (check animal cell
graphic organizer)
How Chromosomes are Formed
 DNA
wrapped around histones creates chromatin
 Who
remembers what chromatin is? (check animal cell
graphic organizer)
 Chromatin
– loosely coiled DNA and histones
How Chromosomes are Formed
 During
cell reproduction, chromatin condenses to form
tightly wound chromosomes
 Chromosomes
– tightly packed bodies of DNA
How Chromosomes are Formed
 Why
must the DNA be so tightly packed?
How Chromosomes are Formed
 DNA
(wrapped around histones) → chromatin → chromosome
How Chromosomes are Formed
Chromosome Structure
 Chromosome
made of 2
chromatids
 Chromatid
–2
identical halves
of a
chromosome
Chromosome Structure
 Centromere
–
where the
chromatids are
attached
Prokaryote Chromosome
 Review:
what are the differences between prokaryotes
and eukaryotes?
Prokaryote Chromosome
 Review:
what are the differences between prokaryotes
and eukaryotes?
 Prokaryotes
do NOT have a membrane-bound nucleus
nor membrane-bound organelles!!!!!!!!!!!!!!!!!!!
Prokaryote Chromosome
 usually
has only 1 chromosome
 Chromosome
has circular DNA
Chromosome Numbers
 Different
organisms have different numbers of
chromosomes
Chromosome Numbers
 Different
organisms have different numbers of
chromosomes
Organism
Chromosome Number
Fruit Fly
8
Pea
14
Human
46
Chimpanzee
48
Goldfish
94
Adder’s Tongue Fern
1,262
Chromosome Numbers
Types of Chromosome
 Sex
chromosomes – determine sex of an organism
X and Y in humans
XX = female XY = males
Humans have 2
 Autosomes
 humans
– all other chromosomes
have 44
Types of Chromosome
Autosomes
 Homologous
chromosomes - 2 identical copies of each
autosomes present in all cells
 One
copy from each parent
Karyotype
 What
is a karyotype?
Karyotype
 What
is a karyotype?
 Photomicrograph
 What
of chromosomes
you made yesterday by cutting and
gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Karyotype
 What
is a karyotype?
 Photomicrograph
of chromosomes
 What
you made yesterday by cutting and
gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 22
2
pairs of homologous chromosomes (44 total)
sex chromosomes
Karyotype (female or male)
Karyotype (what’s wrong with this picture?)
Diploid Cells
 Diploid
 all
cells – cells with 2 sets of chromosomes
human cells (except egg and sperm cells) are diploid
Diploid Cell Abbreviation
 Abbreviated
 In
as 2n
humans 2n = 46 chromosomes
Haploid Cell
 Haploid
 Only
cells – contain only 1 set of chromosomes
sperm and egg cells in humans
Haploid Cell Abbreviation
 Abbreviated
 In
as n
humans n = 23 chromosomes
Diploid vs. Haploid Cells
8.2 Cell Division
Sunda Colugo
8.2 Cell Division
Learning Targets
I will be able to:
 Describe
the events of cell division in prokaryotes
 Summarize
 Describe
the events of interphase
the stages of mitosis
 Compare
plant cells
cytokinesis in animal cells with cytokinesis in
8.2 Cell Division
https://www.youtube.com/watch?v=AhgRhXl7w_g
Prokaryote Cell Division
 Binary
fission – process of cell division used by prokaryotes
 Review:
what shape is prokaryotic DNA?
Prokaryote Cell Division
 Binary
fission – process of cell division used by prokaryotes
 Review:
what shape is prokaryotic DNA?
 CIRCULAR
!!!!!!!!!!
Prokaryote Cell Division
Eukaryote Cell Division
2
types
1.
Mitosis – 1 cell divides into 2 cells with same genetic
material as parent cell
2.
Meiosis – 1 cell divides into 2 cells; each has half the
number of chromosomes (produces gametes)
Cell Cycle
Interphase
 Interphase
 Cells
– time when cells are NOT dividing
spends most of its time in interphase
3 Stages of Interphase
1.
G1 Phase – cells
grow
2.
S phase – DNA
copied
3.
G2 Phase –
preparation for cell
division
Optional 4th Stage of Interphase
 G0
Phase – cells
grow
 Resting
phase
4 Stages of Mitosis
 Review:
what is mitosis?
4 Stages of Mitosis
 Review:
1
what is mitosis?
cell divides into 2 cells with same genetic
material as parent cell
4 Stages of Mitosis
Review: What is the difference between chromatin
and chromosomes?
4 Stages of Mitosis
Review: What is the difference between chromatin
and chromosomes?
Chromatin condenses to become chromosomes!
4 Stages of Mitosis
1.
Prophase
 DNA
shortens and
condenses into
chromosomes
 Nuclear
membrane
and nucleolus
disappear
 Centrioles
 Spindle
appear
fibers attach to
centromere
4 Stages of Mitosis
2.
Metaphase
 Spindle
fibers move
chromosome to middle
of cell
 “metaphase
= middle”
4 Stages of Mitosis
3.
Anaphase
 Chromatids
separate
at centromere and
move to opposite poles
of cell
 Each
forms own
chromosome
4 Stages of Mitosis
4.
Telophase
 Spindle
fibers
disappear
 Nuclear
envelope and
nucleolus reform
 Cytoplasm
divide
begins to
Cytokinesis
 Cleavage
furrow –
where cell membrane
pinches in to separate
2 new cells
 Occurs
in animals
 Cell
plate – forms in
plants
 Precursor
to cell wall
Cytokinesis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Please Make A Terrific Cake
Uncontrolled Mitosis
 Results
in cells that do NOT stop dividing
 Eventually
 cancer
become tumors
8.3 Meiosis
8.3 Meiosis (okapi)
8.3 Meiosis
Objectives
I will be able to:

Compare the end products of meiosis with the end products of
mitosis

Summarize the events of meiosis I

Explain crossing-over and how it contributes to the production
of unique individuals

Summarize the events of meiosis II

Compare spermatogenesis and oogenesis

Define sexual reproduction
Meiosis
Meiosis – cell division resulting in haploid cells
 Produces
gametes (sperm and egg cells)
 Meiosis
has 2 stages
1.
Meiosis I
2.
Meiosos II
Meiosis I
 Called
 Has
reduction division
4 stages………guess what they are
Meiosis I
 Has
4 phases………guess what they are
1.
Prophase I
2.
Metaphase I
3.
Anaphase I
4.
Telophase I and Cytokinesis I
Prophase I

DNA is copied here

DNA coils tightly into
chromosome

Spindle fibers appear

Nuclear membrane and
nucleolus disappear

Synapsis – when homologous
chromosomes pair up

Tetrad – pair of homologous
chromosomes
Early Prophase I
Prophase I
Prophase I
 Crossing-over
occurs here
 Crossing-over
– parts of chromatids break off and attach
to neighbor chromatids
 Allows
for the exchange of genetic material between
chromosomes from mother and father
 Genetic
created
recombination – new mixture of genetic material
Prophase I
Metaphase I
 Tetrads
line up in the middle of the cell
Anaphase I
 Each
homologous
chromosome moves to
opposite poles of cell
 Independent
assortment – random
separation of maternal
and paternal
chromosomes
Prophase I and Cytokinesis I
2
new cells produced
with half the number of
chromosomes (haploid)
(n)
Meiosis II
 DNA
 Cells
is NOT copied
undergo division
similar to mitosis
Prophase II
 Spindle
fibers form
Metaphase II
 Chromosomes
are
aligned along the
middle of the cell
Anaphase II
 Chromatids
separate
towards opposite ends
of cell
Telophase II
 Nuclear
reforms
envelope
Cytokinesis II
 Cytoplasm
4 new cells
splits forming
Development of Gametes
 Meiosis
results in 4
haploid gametes
 Gamete
– haploid
reproductive cell
 Sperm
 Egg
in human males
in human females
Males
4
spermatids form
through meiosis
 Spermatids
develop
into mature sperm cells
through
spermatogenesis
Females
 Oogenesis
of ova
 Ova
1
– production
– mature egg cells
ovum produced
during meiosis
Females
 Oogenesis
of ova
 Ova
– production
– mature egg cells
1
ovum produced
during meiosis
3
polar bodies also
produced
 Ovum
retains most of
the cytoplasm
 Why?
Sexual Reproduction
 Production
of offspring
through fusion of sperm
and egg
 Offspring
are
genetically different
from parents
 Allows
species to adapt
quickly to new
conditions
Asexual Reproduction
 Offspring
come from a
single organism
 Binary
fission and mitosis
are examples