Cells size and shape

There are 200 cell types in the human body; many of them have different shapes.

Many things cause the cell to be its shape, it function contributes to the shape other

o
Cell wall (Not in humans)
o
Cytoskeleton
A cells density is caused by it shape
o
Blood cells are the least dense: plasma, white, then red
o
Bone cells are the most dense

Volume: length x Width x Depth (height) ex. 64cm^3

Surface Area: Side^2 * 6 (# number of sides) ex.96cm^2
o

When you cut these measure into eight pieces the surface area is increased EX

A = 4*4*6 = 96cm^2

(cut to 8) 2*2*6(sides)*8(cubes) 2 b/c to cut into 8 cubes you cut each side into quarters
Important ratio for cells: Area: Volume. As cells get smaller the ratio gets bigger
o
A large cell can have a ratio of 1.5 and a small one can be 6. If you cut the large one into
16 they would have a ratio of 6
Why cells divide

Cells need a large ratio because if they don’t they cannot get all the nutrients into the cell.

A cell needs a lot of H2O and O2 and needs to remove a lot of NH3 (ammonia) and CO2

Since cells are limited a large cell also can’t produce all the proteins needed because so many
are need that there is not enough DNA
o
These are the reasons why small cells are more active than larger cells
Non-dividing cells

Cancer is when cells DON’T STOP believing dividing \

Stem cells are unable to do divide these include

o
Red blood cells die when they lose their nucleus but the new cells are called stem cells?
o
Muscle cells
o
Liver cells normally don’t divide put when you cut it into two it will regrow
o
Brian cells: Central nervous system cells do not duplicate under normal circumstances
Here a normal cell is made then it diferatiates into one of these cells
What controls cell division?

When a cell grows pat a certain point Maturation Promoting Factor (cyclin A+B, dependent kinase)
drives the cell into metaphase by phosphorylation of nuclear lamina.
o
Phosphorylation causes enzymes to turn on which starts the preparation for dividing
Cell cycle – growth and dividing of cell

Interphase > Cell divison

The 2 daughter cells are the same as the parent cell
Interphase (largest) cell prepares for division

G1: gap one (they did not know what happen)
o
Cell doubles in size and makes more protein/enzymes, organelles b/c it is small
o
Cell reaches reach R (restriction) point: the point where MPF comes and triggers the cell
to divide. Cells but not non-dividing cell reach this pint once it does it is destine to divide.

Cyclins are the hormones that cause a cell to divide

GF or MPF: growth factor is a hormone not made by a cell but the surrounding
location or does it no enter the cell?


These two cause cell to pass restriction point
S: synthesis of DNA (replication)
o
DNA and associative protein replicate but there are not chromosomes there are chromatin
that you can’t see

Chromatin dye really easily so if you use pigment dye in S phase you will see 2x
as much color

associated protein: histones the Protein DNA raps around to make a
chromosome

G2:gap two (shortest)
o
Cell begins to organize
o
Centrioles begin to move to poles (only animals)
o
Cytoskeleton is pulled apart so they spindle fibers can be used as spindle fibers. It is
broken down to Alpha and Beta tubulin (Microtubule)

Polar fibers: stretch from pole to pole

Asters: they are attach to centrioles and peripheral fibers which are part of the
cell membrane to hold the centrioles in place

Kinetochore fibers: they connect chromosome to polar fibers
Mitosis AKA karoyokinesis: first part of cell Division
Prophase (longest of cell division)

Chromatid condense into chromosomes
o
Chromosome: two sister chromatid that connect at a centromere
o
To count number of chromosomes you count centromeres

The centrioles separate and lay in the region called the centrosome

Spindle fibers begin to connect

The nuclear membrane begins to disintegrate

Nucleolus disappear

Cell kind of losses it shape because no
cytoskeleton
Metaphase

The spindle fibers are fully connected

the chromosomes go to the equatorial plate or metaphase plate
o

you can see all the fibers

kinetochore

asters not in plants

polar
the chromosome are fully condensed
Anaphase
What is the cause and effect for the chromosomes separating (two
views)

o
contraction of spindle fibers cause the chromosome to move
o
the chromosomes cause the spindle fibers to separate
the chromosomes separate happens at the equatorial plate
o

it pull where the chromosome attached to the fiber
in the diagram they are like -- > |*| < ---because they are being
dragged
o
each half of the chromosomes is still called a chromosome

each one has the same number of chromosomes

the number of centromeres is the number of
chromosomes each cell will get

each spindle fibers goes to each side evenly
Telophase

the cytoskeleton starts to reform

a cleavage furrow is formed that splits the cell
o

middle lamella in plants
each condensed individual (chromosome) sister chromatin
uncondensed and know is a tangle of DNA

a nuclear envelope reforms around the tangle

the spindle break apart

nucleuses become visible in each cell
Cytokinesis: when cytoplasm splits so there are two new cells

last part of M phase (mitosis + cytokinesis)

normally accurse at the same time as telophase

in most animal cells the cell membrane in pinched in by a cleavage furrow made by
microfilaments
Plants

no centriole or centrosome there is an area where spindle fibers arrange

in telophase many little vesicles form in the middle called a cell plate

o
In the middle there is pectin: a sticky hetropolysaccharide
middle lamella: Each vesicle lines up and joins to getter forming two single membranes
with pectin in between
o
after the pectin in the membranes is replaced by the primary cell wall then the secondary
cell wall replace it
Cell division in prokaryotes


E. Coli most important bacteria
o
Found in the large intestine they produce k2 vitamin
o
bacillus: rod shaped cell
part of cell has less ribosomes under electron microscope there is a clear part of the cell
o
the DNA is in that part

The bacterial chromosome is round (so there are no end parts )

nucleoid: the rejoin that DNA is in not a organelle

salt, ph, heat all effect the bacteria division
o
if the condition are just right then the divide every 20 minutes
Binary fission

how a bacteria divide

messome: when the Membrane fold and the chromosome attaches to it which starts its
replication

we call this theta replication
o
Since bacteria DNA is a big circle complementary to a smaller inner circle the inner
circle pulls out and DNA polymerase brings the nucltiotides to make new DNA strains

After pheta replication the mesosome

Two daughter cells are formed as they move apart from each other and the cell will become very
narrow (long horizontal rectangle)

o
They mesosomes pinch in so much that it makes a wall
o
Origanlly the cell was
certain fungi do binary fission
Binary fission in a prokaryote.
1: The bacterium before binary fission is when the DNA tightly coiled.
2: The DNA of the bacterium has replicated.
3: The DNA is pulled to the separate poles of the bacterium as it increases size to prepare for splitting.
4: The growth of a new cell wall begins to separate the bacterium with the help of FtsZ ring
5: The new cell wall fully develops, resulting in the complete split of the bacterium.
6: The new daughter cells have tightly coiled DNA, ribosomes, and plasmids.
Mutations

sudden mistake in the making of an organism
o

normally happens in meiosis
o

the nuclides are working a lot and messes up
mutagen: mutation causing agent or mutation generating agent
o

not always bad
Carcinogen: causing cancer (cancer is caused by mutation?)
radioactive, chemicals (oxidizers), UV rays, X-rays, heat
o
all are high energy, the high energy causes the DNA to change it causes the DNA to
break and they may repair the wrong way
o

happens at a very sensitive time in the cells life
know the types of mutations
Medallion genetics

Gregory Mendel born in 1822 in a small town in the chez republic
o
in brome, born to a humble family
o
child prodigy

applied to go to university of Vena Austria for math


he then became a monk he had a lot of time for many things like math and science
o

did very well then wanted to become a teacher failed the exam
he spend time on researching how Hereditary information is passed on
No one understood what he was talking about all his stuff was lost and in the 1900s a
Swedish guy rediscovered his stuff
o
he was alive at the same time as Darwin genetics contributes to evolution
o
so the field of genetics is about 152 years old
He used pee plants (Pisum sativum)

pee plant structure
o

a regular flower
Has four different flower that have constrict rings
o
Sepal: outer most ring it protects the bud
o
Petals: second outer most has nectar fragrance and beautiful colors that help attract
pollinators like bees
o
Stamen: third ring made of pollen sack and anther (pollen is made)
o
Carpel/pistil: fourth ring, inner most. Has 3 parts
o
Ovary: holds ovule which holds the egg
o
style
o
stigma: pollen lands on here then goes down the style to the ovule where the eggs
(ova) are held



ovary become the fruit

ovule become the seed coat
pea flowers are closed so they have a pollinator and ovary in the same plant
o
he can tell what produces what
o
Purebred plants: plant is one that always produces offspring with the same form of a trait as the parent
he choose the pea plant because it self-polentas
o
he was able to see what mated with what because if it was self-pollinated it can be coming
from far away
o
he can control all the variables and can engineer pollination
5//2 get this stuff

he saw the variation in pea plants 7
o
short or tall
o
white flowers or purple flowers
o
green pea pods or yellow pea pods
o
smooth or ruff pod
o
smooth or ruff seed
o
shape of the seed
o
where the flowers are positioned on the plant

he only dealt with these 7 traits,

he had two plots
o
one plots had yellow seeds one plot had green seeds


the both bloom within six week
he goes to one plot and opens all flowers in the first plot with yellow and cuts the anthers off
o
the stigma is what make the pollen so without it cannot reproduce

he goes to the green plot and takes all the pollen into a jar

he then take the green plant pollen and puts it onto the stigma of n the first yellow pee plants

in a few days the flowers dry out and fall
o
in a few more days he sees a pod growing in plot a flowers

he looks at all the pods (seeds that were made) he see that even though he used green the
seeds are all yellow

he takes all the hybrids having a question about where did the green trait go
o

he replants them and does not do anything to them
some were green some were yellow
o
he saw that whenever he dido this experiment they had the same ratio of yellow 3000:
green 1000
Phenotype: the outside type of appearance
o
in our story they are yellow and green
Parental generation:

yellow seeds X green seeds
o

first filial: first generation
o

O with X in it shows it self-breed
second filial: the second generation
o

they were all yellow
yellow O with X in it
o

X shows mating
3:1 yellow to green
from this he saw that there was something physical passing information on
o
they called it elementary at first but changed it to genes
genotype: is the genetic makeup of a cell, an organism, or an individual (i.e. the specific allele makeup
of the individual) usually with reference to a specific character under consideration

he knew there were 2 genotypes from a male and female because of his experiment

gamete + gamete -> zygote

Y + Y -> Y

gametes are made in meiosis

P; YY x yy

o
gamètes Y,Y x y,y
o
dominate: Y
o
recessive: go into the background lower case y green
if YY and yy breed than you get Yy Yy Yy Yy
o

(Y Is dominent)
this generation is called F1
now cross Yy x Yy
o
YY , Yy, Yy, yy
o
1
o
1,2,3 is yellow
2
3
4
o
4 is green
o
F2 generation
o
the ratio is called the serotype get this

YY = homozygous dominate

yy = homozygous recessive

Yy = heterozygous

first law of medallion genetic: law of segregation (two genes get separated)
o
in the process of gametes formation the two gene control a trait are separated from each
other
5/6
1.
put down P (parents) P: BB x bb
double white fur is albino
2. gametes B x b
3. F1: Bb
4. genotypic ratio is all black and all heterozygous

B) P: Bb x Bb
o
Gametes: B,b x B,b

F1; BB, Bb Bb, bb

phenotypical 3:1

genotype ratio 1:2:1
2

P: must have one big P?, other is same P?
o
Gametes, P,? x P,? (P,p x P,p)
o
F1; P?, pp (has to have this to make dominate trait)
o
because the ratio 4:2
o
there is a question because Pp can still be it or PP

o
can’t be PPx pp or it is Pp x pp so it make yellow eyes
testcross is when you can find out what the unknown trait is by see what it makes with a
homozygous recessive
There is no definite answer because it does not have to follow probability
Incomplete Dominance

4 o'clock flowers the nice looking flowers at 4 the open up
o
some are red some are white
o
if you make a red flower and a white flower and cross them
o
RED x White

all of them are pink

if you self-pollinate pink flowers some are white, red, or pink
o
5/6a

P; RR x R'R'

gamete R x R'

f1: RR'
' means equal’
o
self-pollinate this one
o
RR, RR', RR', R'R'
Third part of genetics

each person is a package of traits
o
one part from each parent

if you want to look at 100 traits start with two

5/6b
5/7



yellow, tall x green short
o
f1 all of them were yellow and tall
o
f2 green tall, yellow short, yellow tall, green short
o
9000
o
he always get the ratio of 9;3;3;1
3000
3000
1000
YYTTx yytt
o
gametes: YT YT
o
f1 Yy Tt x Yy Tt
o
gametes YT YT yT yT x YT YT yT yt
yt yt
R.Punnett 5/7a
law of independent assortment
4/10

codominance
o
humans have white blood cells that make antibodies AKA immunoglobulin’s=I
o
globin is a protein known as I^A and there is I^B I^O


these are genotypes (codes for these
I^O can’t make A or B

Genotype

I^AI^A
A

I^A I^O
A

I^B I^B

I^O I^O
O

I^A I^B
AB
phenotypes
B

I^B I^O

codominance happens in AB because each is dominant so both are seen

incomplete dominance this makes a third possibility
B
rabbits

there are four colors for fur
o
black albino, albino, brown, and ...
multiple alleles


alleles: different possibilities for a gene
o
they are options of a type of gene to make something
o
like there is a gene for color that can make black or white
here there are
o
A
o
B
o
O

human population has all three of these but a person can only have two at a time

if I^A I^O then write it as I^Ai

O is ii
Multiple genes (polygenic inheritance)

to be a giant corn you may have AABBCCDDEE x aabbccddee

you can have many genes controlling a trait
o
this one will be a short corn
Meiosis

AKA reduction division
o
the main objective of this division is to reduce the number of chromosomes



two types of cells
o
somatic cells; body cells
o
sex cells; gametes
every cell in the body has two sets of chromosomes
o
somatic cells

o

diploid cells; 2n
gametes


if 8 you get 4
monopolies or haploids; n
gamete types
o
egg or ova cells; n
o
sperm cells; n
fertilization-join egg and sperm your get a zygote;2n
o
gametes are made so you can do fertilization
---Height in humans in polygenic inheritance
Continuous variation; it is when it is more of a kind in the middle
---
humans have 46 chromosomes
o
23 pairs of chromosomes one from each parent
o
23 pairs of homologues chromosomes
o
homologues means identical shape, size, similar sequence



the location of the centromere cases the shape

each piece of a pair is a homolog

gametes have 23 homolog
you can stop them when they are doing metaphase so you can take photos of the cells
o
there in pairs
o
each homolog has the same shape
two cycle in Meiosis
o
Meiosis I and Meiosis II

starts with prophase I

metaphase I

anaphase I

telophase I

------------------

cytokinesis AKA interkensis for the intermediate cytokinesis in

prophase II

metaphase II

telophase II

cytokinesis
Meiosis 1; reduce amounts of chromosomes from 2n to n
You have to be at least diploid to do Meiosis
Reduction division

prophase one
o
synapsis when the homolog go to each other

they condense when they do this

each homologue is a chromosome so it pairs with the other

tetrad: the homologous pares which are 2 chromosome so 4 chromatid
o
they cross over; exchange equal amounts of genes
o
chiasma is the point where the homologue cross over
o



plural chiasmata normally many cross over

cross over of sister chromatins does not affect it

if it crosses over with not identical chromosome then there is variation
genetic recombination
metaphase one
o
the homologue line up one the equatorial plate
o
so each homolog faces its homolog
anaphase one
o
each homolog is pulled to the end
o
this is the step where the cell becomes 1n
Meiosis 2

interphase 2
o

prophase 2
o


chromosomes still hold on to the sister chromatin
metaphase 2
o
just regular non related chromosomes
o
they line on the equatorial plate singled filed
anaphase 2
o

in inter phase the DNA duplicates?
each sister chromatin goes to each poll
telophase
o
4 cells are made
Differences in mitosis and mistosis

mitosis identical duplicated chromatin

meiosis; the red chromosome don’t have to be opposite sides
Gametogenesis

male: spermatogenesis

female: oogenesis