Transcript Cells - STA304

Chapter 5
The human organism and the
perpetuation of life.
Topics:
The cell and its functions
Cell division (mitosis & meiosis)
Tissues, organs and systems
The Reproductive System
About Cells
• The cell is the basic unit of structure and
function in living things
• Cells are usually microscopic, but range
from the size of a bacteria to the size of an
unfertilized ostrich egg.
• Living things contain one or more cells
– Protozoans contain a single cell
– Humans contain billions of cells
CELL PARTS
• The various parts of cells are known
collectively as CELL PARTS.
• Cell parts are structures inside a cell that
are too small to be living, but which
together allow a cell to live.
• Cell parts include:
•
•
•
•
•
Membranes, that surround the cell and nucleus.
Filaments, tubules and fibres that
Macromolecules, like the DNA of chromosomes.
Fluids, like the cytoplasm.
Organelles and other structures inside the cell.
Three Main Parts of a Cell
• A cell usually has three distinct areas or
layers:
– The membrane
– The Cytoplasm & Organelles
– The nucleus & Chromosomes
Membrane
Cytoplasm
(with organelles)
Nucleus
(with chromosomes)
Function of the Cell Membrane
• The cell membrane is a flexible barrier that
that surrounds the cell and allows the cell
to interact with its environment
– Forms a protective barrier
– Helps absorb nutrients and useful substances
– Helps eliminate wastes and other materials
produced inside cells
Drawing of a cell membrane
Copy the “simplified diagram” from the blackboard
Part 2: The Cytoplasm & Organelles
• Together, the cytoplasm and organelles
are sometimes called protoplasm
– The cytoplasm is the liquid portion of the cell.
• It is a complex mixture of materials: water, gases,
wastes, nutrients, raw materials
– The Organelles
• Suspended in the cytoplasm are many tiny
structures called organelles. Each organelle has a
specific function.
The Organelles
• Mitochondria (sing. mitochondrion).
• Endoplasmic reticulum
– Rough
– Smooth
•
•
•
•
Ribosomes
Golgi Apparatus
Lysosomes
Vacuoles
Mitochondria
• The mitochondrion is the powerhouse of
the cell. Here chemical energy is released
by the break down of food particles.
• It is a bean-shaped organelle with an
internal membrane folded into many
“cristae” .
I am very energetic!
And cute as a bean too!
Endoplasmic Reticulum
• The “ER” or Endoplasmic Reticulum is a
network of tubes and membranes that
runs through the cell. Its purpose is to
transport materials quickly through the cell
• Rough ER
– Has ribosomes
• Smooth ER
– Has no ribosomes
ER Transport system at your service!
For when it absolutely, positively has to get
to the ribosomes quick as possible.
Ribosomes
• Very tiny, round organelles associated
with protein synthesis
• They help manufacture the cell’s proteins.
We are very small, like
beads. Sometimes we
hang around the
endoplasmic reticulum
Golgi Apparatus
(A.K.A. Golgi body or Golgi complex)
• A network of membranes, similar in
appearance to the ER
• Its purpose is to modify and “package”
proteins that will be secreted.
• Also makes digestive enzymes
I look like sort of like a
stack of pancakes with
blobs of syrup falling off!
Lysosomes & Vacuoles
• These are storage areas within a cell
• Lysosomes hold digestive enzymes that
help the cell metabolize food. When a cell
dies, the digestive enzymes help dissolve
the dead cell
• Vacuoles store food or water
Let’s get together
I’ve got the digestive enzymes
And I’ve got the food
And have a feast!
Part 3: The Nucleus
• The nucleus consists of:
– The nuclear membrane or envelope (with tiny
nuclear pores in it)
– The nucleoplasm
– The chromatin material
• AKA chromosomes
– The nucleolus
Hey!
I am, like, in control, man!
All the organelles get their
instructions from me.
Exercise
• Colour, label and give the functions of the cell
drawing.
Typical Human Cell
A. Cell Membrane
B. Smooth ER
C. Cytoplasm
D. Mitochondrion
E. Ribosome
F. Nucleus
G. Golgi apparatus
H. Lysosome
I. Endocytosis / Exocytosis
J. Nucleoplasm or “matrix”
(containing chromatin)
K. Nucleolus
L. Nuclear membrane “envelope”
(with nuclear pores in it)
M. Rough ER
DNA
a helix is a spiral
shape, similar to
a spring.
DNA is a molecule, shaped like a
double helix, usually found inside
the cell’s nucleus.
• Facts about DNA
– Chromosomes are made of DNA
– Genetic information is stored on DNA
– DNA is the only large molecule that is
able to copy itself.
A Helix
• Trivia:
– DNA stands for deoxyribonucleic acid.
Carbon atom
(gray)
Hydrogen
atom (white)
Phosphorus
atom (orange)
Oxygen atom
(red)
Nitrogen
Atom (blue)
Portion of a Model of
a DNA Molecule
DNA contains carbon, hydrogen,
oxygen, nitrogen and phosphorus
Simplified drawing of
a DNA Molecule
The atoms are arranged into a sugar-phosphate backbone,
and four types of nitrogen-containing bases.
• Some people
compare the
structure of DNA
to a twisted
ladder.
• The sugar and
phosphate form
the sides, and the
base pairs make
the rungs or
steps.
Genes
• A Gene is a segment of DNA that contains
the genetic information to carry out a
particular job.
• That is, to make a particular protein or to control a
particular feature.
• A Genome is a complete set of genetic
information.
• Enough information to make a complete body and
all the cells in it.
• A genome can contain thousands of genes
Genetic Diversity
• Genetic Diversity is the differences
between individuals, achieved by all
possible genetic variations of a particular
species.
• All organisms have different individuals.
• The more the differences, the greater the genetic
diversity.
Assignments
• Textbook:
• Read pp. 125 to 127
• You may try questions 1 to 7 on p. 152
• Workbook
• Do pages 67 to 70
Mitosis & Meiosis
Topics:
•Mitosis Overview
•Meiosis Overview
•Mitosis vs. Meiosis
Cell Cycle
The life of a cell:
• Cell grows
– Prepares for division
(mitosis),
– Divides to daughter
cells,
– Cycle begins again
OR
• Cell Dies
Overview of Mitosis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
2 Main Events of the Cell Cycle
• Interphase: Cell grows & prepares
for Mitosis (see previous slide for
diagram)
– Prepares 2 ways
• Replicates chromosomes
• “Tools” for mitosis are produced
• Mitosis: Cell divides to form two
genetically identical cells
– One copy of chromosomes goes into
each new cell
Mitosis main points
• Starts as diploid
– two copies of each chromosome (total=46 in humans)
• Ends as diploid
– One diploid parent cell makes two identical
diploid copies of itself. (total=46 in humans)
• Very small portion of cell life spent in mitosis
(6%)
• All living and growing cells undergo mitosis
Meiosis
Meiosis main points
• Meiosis Enables sexual reproduction
• Starts with diploid cells
– Two of each chromosome type (46 in humans)
• Ends with haploid sperm or egg cells.
– Only one copy of each chromosome (23 in humans)
• Only cells in testicles and ovaries undergo
meiosis.
• Meiosis increases genetic diversity due to
crossing over of genes, and the mixing of
two different sets of genes after fertilization
Mitosis in Detail
• Remember:
– Mitosis is normal cell division
– It is part of the cell cycle
Cell Division
(MITOSIS)
Phases in the Cell Cycle
I
PM
AT
= INTERPHASE
Remember:
Preparing for Mitosis
= PROPHASE
= METAPHASE
= ANAPHASE
= TELOPHASE
(and cytokinesis)
Where’s
It will help
my
Pee MAT?
you keep
Undergoing
track of the
Mitosis
5 main
phases of
a cell’s life
The Cell Cycle
G1 S G2
M1
M2
M3 M4
Cytokinesis:
Prophase:
Metaphase:
Interphase:
Anaphase:
Telophase:
The
The
The
The
cell
nuclear
chromosomes
Cell
chomatids
chromosomes
splits
grows
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split
and
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and
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and
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split.
to
spindle
fibres
opposite
attach
poles
to them .
• Mitosis: Short video
Interphase
• Interphase: Cell prep for mitosis (G1, S,
G2)
– Cell spends ~94% of life in interphase
Photograph of Interphase
Stages of Mitosis
Prophase: (Prep Phase)
• Chromosomes coil and become visible
• Nuclear membrane breaks down
• Spindle fibers assemble
Photo: Early Prophase
Chromosomes
Stages of Mitosis
• Metaphase (Middle)
– Chromosomes line up in the middle of cell
– Spindle fibers bind to the centromere
Photo: Metaphase
Spindle (fibers)
Centrosome
Chromosomes
Equatorial Plane
Stages of Mitosis
• Anaphase (Apart)
– Spindle fibers pull chromosomes to opposite
sides of the cell
Photo: Anaphase
Centrosome
Chromosomes
Stages of Mitosis
• Telophase (Two)
– Cell begins to split into two cells
– Nuclear membranes reform
Photo: Telophase & Cytokinesis
Cleavage
furrow
Nucleus
forming
Cells Divide
Stages of Mitosis
• Cytokenisis
– Cytoplasm is split in half
– Each cell has identical chromosomes
Annoying Mitosis Song video
• During your lifetime, mitosis has created
the billions of cells of cells that make up
your body.
• Mitosis is simple and nearly flawless
(errors in mitosis are extremely rare)
• Mitosis gives each cell its own copy of all
your genetic information (your DNA)
• Simple organisms (like the amoeba) can
even reproduce by mitosis.
If mitosis works so well, why do we
need meiosis?
• Sexual reproduction helps a species
survive.
– It allows traits from two individuals to be
mixed, giving greater diversity.
– Greater diversity gives a species a better
chance of surviving hard times.
• In order to have sexual reproduction, there
must be a way of reducing chromosome
numbers.
– You have 46 chromosome, your spouse has 46
chromosomes
– If meiosis did not occur, your children would have
92 chromosomes
– Your grandchildren would have 184 chromosomes
– Your great-grandchildren 368, and so on…
– This would soon lead to genetic problems like birth
defects or bad mutations.
• Meiosis strips away half of the
chromosomes
– In humans this produces eggs and sperm with
only 23 chromosomes (instead of 46)
• Fertilization restores the chromosomes
– When a human egg is fertilized, it gets 23
chromosomes from the mother and 23 from
the father, restoring the normal 46
Meiosis
G1 S G2
MEIOSIS
st
1st1Interphase:
Metaphase:
Prophase:
The
The
The
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nuclear
Cell grows
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and
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Meiosis
G1 S G2
MEIOSIS cycle 1
11ststAnaphase:
Metaphase:
The
TheWHOLE
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CHROMOSOMES
line up near
migrate
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to opposite
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do
(equatorial
not split yet!
plane) and spindle
st
attach to them .
1fibres
Telophase:
The chromosomes reach the
poles, new nuclei begin to form,
the cell prepares to split.
Cytokinesis:
The cell splits into two new cells
Meiosis
G1 S G2
MEIOSIS cycle 2
Prophase & Metaphase
Anaphase:
Telophase:
Cytokinesis:
The original
chomatids
chromosomes
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split
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Assignments on Cell Division
• Textbook:
• Read pages
• Try questions 8 to 15 on page 153
• Workbook:
• Do pages 71 to 74
Cell Specialization
• As your cells divide they also become
different from each other. They specialize.
• Some cells become blood cells, some become
muscles, some become bone cells, and some
become brain cells.
• A group of similar cells, with a common
function, is called a tissue:
Levels of Organization
Strings?  make up  Quarks  make up  Subatomic Particles
Atoms  make up  Molecules  make up  Macromolecules (like DNA)
Cells make up  Tissues  make up  Organs  make up Systems
Biosphere of our Planet in our Solar System in our  Milky Way Galaxy
in the Local Galactic Group  in the  Virgo Supercluster in theUniverse
4 Main Tissue Groups
• Although you may have hundreds of tissue
types, they all belong to four main groups
of tissues
• Epithelial Tissues cover and protect your body
and its organs.
• Connective Tissues bind and support the organs
and the body. They also transport oxygen and
nutrients.
• Nerve Tissues control and guide the body, and
communicate between body parts.
• Muscle Tissues make body movement possible
Epithelial Tissues
• Just a few of the many types of epithelial
tissue:
•
•
•
•
•
Skin
Stomach lining
Intestinal lining
Arteries and veins
Kidney tubules
Connective Tissues
• There are also many connective tissues,
such as:
•
•
•
•
•
Bone tissue
Cartilage
Tendons & Ligaments
Fatty tissues
Blood
Nerve Tissues
• Nerve tissues make up much of:
• The Brain
• The Spinal Cord
• The Nerves
Muscle Tissues
• There are 3 main types of muscle tissue
• Skeletal Muscle:
– The muscles attached to bone. They make movement
possible.
• Smooth Muscle:
– Found inside us, smooth muscle pushes things through
our organs (peristalsis).
• Cardiac Muscle:
– Found in the heart, cardiac muscle is very durable.
Organs
• An organ is a structure composed of two
or more tissue types performing one or
more specific actions
• In other words: it’s a bunch of tissues working
together!
• Examples of Organs and their function
•
•
•
•
•
Stomach:
Intestine:
Lungs:
Heart:
Skin:
grinds up food
absorbs nutrients
absorb oxygen from the air
pumps blood
protects our bodies
Organ Systems
• A system is a group of tissues working
together to accomplish a common function
• Our body has many systems, for example:
• Our cardiovascular system which circulates our
blood and transports nutrients to cells.
• Our nervous system which controls our
movements, thoughts, decisions and responses
• Our reproductive system, which enables sexual
reproduction
Examples of Organ Systems
(Similar to table on page 139 of Textbook)
System
Function
Cardiovascular
Circulates blood, transports nutrients, transports wastes
Digestive
Breaks down and absorbs nutrients, eliminates solid waste
Endocrine
Uses hormones to control organ performance.
Excretory (Urinary)
Eliminates the body’s liquid wastes
Immune
Protects us against foreign organisms (bacteria, viruses etc.)
Lymphatic
Helps the immune system to protect us. Drains and excess
fluids from the body and filters the fluids back into the blood.
Musculoskeletal
Provides the body with support, mobility and protection
Nervous
Controls the entire organism (thoughts, decisions, memories)
and relays information to various body parts and interacts with
the environment through the sensory organs
Reproductive
Enables sexual reproduction. Linked to the endocrine system
Respiratory
Helps the body absorb oxygen and expel carbon dioxide
Exercises on Tissues
• Textbook:
• Read pages 136 to 139
• Try question 16 to 18 on page 153
• Workbook:
• Do pages 75 and 76
Reproductive Systems
•Puberty
•Female: Menstrual & Ovarian Cycles
•Male: Erection & Ejaculation
•Hormones
Puberty
• There are major mental and
physical changes that occur
during your life stages
• Humans life stages:
– Before birth:
zygoteembryofetus then
– Birth:
babychildadolescent
adult and finally an old person
• Puberty occurs between
childhood and adolescence
Puberty cont.
• Three categories of change
occur at puberty
– Anatomical
• Shape of body fat, muscles
skeletal
– Physiological
• Genitals mature
(external & internal)
• Able to procreate
– Psychological
• Clash with authority
• Identity change
• Libido (sex drive)
Female Reproductive System
(internal organs front view)
• Ovaries
Connected to
the uterus by
Fallopian tubes
• Uterus
Also called the
womb.
Female Reproductive System
(internal organs side view)
Fallopian Tubes
Ovaries
Uterus
Endometrium
Uterine Cervix
Vagina
Clitoris
Female Reproductive
System
• You have already learned
the different parts
– so here’s what they do
• There are two cycles
– Ovarian Cycle
• Egg release
– Menstrual
• Getting your period
• Removes and then renews
the lining of the uterus
Don’t mix them up!
• The two cycles occur at the same time,
and are often confused with each other,
but…
• They each rely on different hormones
– Ovarian: FSH and LH
– Menstrual: Estrogen and progesterone
• The Ovarian cycle has to do with releasing eggs.
• The Menstrual cycle has to do with preparing the
uterus.
Ovarian cycle
Menstrual cycle
• Ovarian cycle, egg
released
(around day 14)
• Body temperature
changes slightly
during cycles
• Hormone levels in
blood change.
Menstru.
Proliferation Phase
Secretory Phase
• Menstrual cycle:
Thickness of the
endometrium
(uterus lining)
grows.
(from about day 6 on)
The ovarian cycle
• All ova (eggs) are produced
before a girl is born
• The ovarian cycle is simply
the release of these eggs
– From the ovaries
– Every 28 days (approx.)
• When a woman begins to
run out of eggs, Menopause
may occur.
• The ovarian cycle stops.
• Then the menstrual cycle will
change or stop.
• Many hormone changes occur.
Oogenesis
It’s pronounced oh-oh-genesis, not ewww-genesis!
• Egg production begins before a woman is
even born!
– 15 to 28 weeks in utero/fetus, Oocytes (diploid junior
egg cells) are produced.
– Then wait until puberty to be released one at a time
• Each month an oocyte undergoes meiosis to
become one haploid ovum (egg cell). Its three
“sister eggs” die.
The menstrual Cycle
• Directly related to the ovarian
cycle
• Vaginal bleeding occurs
– ~Every 28 days
– Endometrium (lining of uterus is
discarded)
• The endometrium is meant to
– attach to fertilized egg
– Feed the growing fetus
• If no fertilization occurs
– Bleeding, caused by loss of
endometrium occurs
Menstruation
Proliferation Phase
Secretory Phase
See pages 146-147
Day
1
2
3
4
5
6
7
8
9
10
11
12
13
14 O
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Menstrual Cycle
Ovarian Cycle
Bleeding, due to expulsion of
endometrium and unfertilized
An Ovarian follicle begins to mature.
ovum.
Progesterone decreases due to
deterioration of corpus luteum The Pituitary secretes FSH (Follicle
Stimulating Hormone)
The growing follicle secretes
estrogens, which stimulates the
Estrogen is produced by a new pituitary to secrete more FSH and LH
ovarian follicle. (Lutenizing Hormone)
Endometrium Thickens.
Ovulation: Follicle bursts, resulting in a surge in hormones.
Endometrium continues to
thicken.
Ovarian follicle becomes the Corpus
Lueteum.
Progesterone is secreted by Corpus Luteum secretes progesterone,
corpus luteum . stopping the pituitary from releasing
any more FSH and LH
If the ovum is not fertilized, the corpus
luteum begins to deteriorate. It stops
producing progesterone, so the
Progesterone decreases due to pituitary starts producing FSH again
deterioration of corpus luteum
Assignments and Exercises
• Text book:
• Read pages 143 to 148
• Workbook:
• Page 77 to 82
Male Reproductive System
Reference page 149
Male Reproductive System
• You have already learned the
different parts
– so here’s what they do
• Why do we need an erection?
– 2 things
• penetrate/get into the vagina
• Deposit sperm near the uterus
– Where the egg is waiting
Male Reproductive
System
• What is ejaculation?
– Occurs at sexual climax
• (most pleasure)
– Involuntary wave of
contractions from
• epididymis, through the vas
deferens, prostate, seminal
vesicles and finally out the
urethra (know this)
• seminal vesicles provide 70% of
the fluid in ejaculate which acts
as a lunch for sperm among
other things
What about sperm?
• Spermatogenesis occurs in the
testicles
– The whole process can take up to 72
days!
– Starts as diploid cells in seminal
tubes of, testicles
– After meiosis they work through the
middle of the tubes.
– All the way the epididymis
» 6m long voyage!
– There they get their tails and they’re
ready for action
• Bonus: What is a scrotum good for?
– Sperm cooling
• Sperm grow optimally a 3 degrees C lower
Hormones
• Hormones are in control of:
– the reproductive system
development, cycles etc.
– Nearly all growth, and
maintenance of your body
systems
• Similar to your nervous system
– They communicate but the
messages are slower and last
much longer.
Hormones
• Produced and secreted by glands
– Male hormone gland: testicles
• Produce testosterone
– Female glands: ovaries
• Produce estrogen and progesterone
• The most influential gland
– The “gland daddy” of them all
– The pituitary
• Because its hormones control sex glands and:
–
–
–
–
–
–
–
–
Growth
Blood pressure
Some aspects of pregnancy and childbirth
Breast milk production
Sex organ functions in both women and men
Thyroid gland function
The conversion of food into energy (metabolism)
Water and osmolarity regulation in the body
Very Important!
Long
term
accumulation
Progesterone
isInitiates
a feedback
Puberty
Then
helps
regulate of
estrogen
causes
to the pituitary,cycles
causing
In Both
to
in itaSexes!
woman
development
of breasts,
reduce the
LH after
& FSH
puberty
enlargement of hips,
accumulation of fatty
by
Effects tissue and certain
psychological changes.
The “Big 6” Hormones
Hormone Name
Secreted
FSH
Pituitary
(Follicle Stimulating Hormone)
LH
In female initiates follicle production
Pituitary
(Luteinizing Hormone)
Progesterone
Helps initiate puberty
Helps initiate puberty
In female releases egg & heals follicle
Ovaries
Inhibits LH & FSH
(corpus luteum)
Thickens endometrium
Estrogen
Ovaries
Female Hormone
(A.K.A: Oestrogen)
(developing follicle)
Controls female secondary
characteristics, affects endometrium
Testosterone
Testes
Male Hormone
Controls male secondary
characteristics
Kisspeptin
Pituitary
Helps Initiates Puberty
Primary vs. Secondary sex characteristics.
• Primary Sex Characteristics
Affect the sex organs
Genital organs develop and mature (M/F)
Menstrual cycle starts (F)
• Secondary Sex Characteristics
Affect other parts of
the body
Breasts develop (F)
Larynx enlarges (M)
Pelvis widens (F)
Facial hair appears (M)
Fatty tissue accumulates (F) Muscles grow (M)
Bone density increases (M)
Pubic and underarm hair appears (both)
Psychological changes occur (both)
Effectiveness of Birth Control Methods
“worst case” failure rates
•
•
•
•
Vasectomy
Withdrawal*
Withdrawal**
Condom
1%
96%
27%
12%
* As typically done
** as correctly done
The actual failure rates
depend on brand and quality
and the correct use of the
contraceptive product. Actual
failure rates may be lower
•
•
•
•
•
•
•
Oral Contraceptive
2%
Contraceptive patch
1%
Injections / vaginal ring 2%
Tubal ligation
1%
Spermicides
21%
Female condom
12%
Diaphragm & spermicide 18%
• Mini-pill
• Morning after pill
• IUD
6%
??%
6%
Assignments on Reproduction
• Textbook:
• Read pages 149 to 151
• Do questions 19 to 34 on pages 153 and 154
• Workbook
• Do pages 82 to 88