Transcript Chapter 8 Notes

Unit 2 Notes
Cellular Transportation And The
Cell Cycle
Cell Transportation:
2 main types
1. Passive transport: Does not require
energy from the cell
Moves downhill, with the concentration
gradient
Cellular Transportation
Type 2

2. Active Transport: Requires energy to
occur.
Moves uphill, against the concentration
gradient.
Passive Transport
(No energy required)
3-Types
1st Type Passive Transport

Simple Diffusion : Movement of any
substance from areas of higher to lower
concentrations

diffusion animation
2nd Type Passive Transport

Osmosis: Movement of water from
areas of higher to lower concentrations
3rd Type Passive Transport

Facilitated diffusion: Movement of
substances from higher to lower
concentration with help from a protein
molecule
Animation: How Facilitated Diffusion Works
2-Types of Active Transport
(Energy Required)
1. Exocytosis: The expulsion of particles
from the cell.
2. Endocytosis: surrounding and engulfing
particles.
Pinocytosis: Cell drinking – the cell
takes in liquids.
Phagocytosis: Surrounding and
taking in of large particles.
Phagocytosis

Animation: Phagocytosis
Solute vs Solvent

Solute: The dissolved substance in a
liquid.

Solvent: The liquid that the solute is
dissolved in: Usually water
Types of solutions
Isotonic solution



Concentrations of
solute are equal in the
cell and the solution.
(cell=solution)
Water moves back
and forth at the same
rate.
Water in =Water Out
Hyp-O-tonic solution
(Hyp-Ohh no I’m swelling-tonic)
HypOtonic: Concentrations of solute are
higher in the cell than in the solution (cellhigher, solution-lower)
 Water moves into the cell.
 The cell swells and can burst.

Hypertonic Solution

Concentrations of
solute are lower in the
cell than in the
solution (cell-lower,
solution-higher)

Water moves out of
the cell.
The cell shrinks.

Limits to cell size

A cells size is limited, so organisms grow
by cellular division.

The cells of a baby are the same size as
the cells of an adult.
So… Why Can’t cells just grow
larger???
Three factors that limit the growth
of cells
1. Diffusion across cell surface.
 2. Shortage of DNA.
 3. Surface to volume ratio.

Diffusion

Diffusion is efficient over short distances,
but becomes inefficient and slow over
large distances.

So…cells that are large have a more
difficult time getting nutrients into the cell
and waste products out of the cell.
DNA

A cell cannot survive without sufficient
amounts of DNA to make necessary
proteins

Unusually large cells must have multiple
nuclei in order to supply needed DNA
Surface Area to Volume Ratio

As a cell’s size increases, its volume increases
faster than its surface area
Cell Reproduction

Mitosis: Asexual reproduction (Cell Cycle)

The process by which one cell divides into
two cells, both identical to the original
parent cell
The Dreaded “C” Words!
Chromatin
 Chromosomes
 Chromatid
 Centromeres
 Centrioles

Chromatin

Relaxed DNA.
Chromosomes

Condensed DNA.

DNA that is preparing
to undergo cellular
division

Can now be seen with
a microscope.
Chromatids and Centromeres

Sister Chromatids: Halves of a duplicated
parent chromosome.

Centromeres: The structure that joints two
sister chromatids.
Chromatin and Chromosome
Centrioles- Produce the spindle
and aid in replication
The Cell Cycle

The process of asexual reproduction
(mitosis) of the cell

Contains three major parts

1. Interphase 2. Mitosis 3. Cytokinesis
The Cell Cycle
Part One of the Cell Cycle
Interphase

The cell spends the majority of its life in
interphase.

A time in which the cell is preparing for
division.
Interphase
3-Parts

G-1: Maturation.

S-Phase: DNA replicates - makes a
duplicate copy of itself.

G-2: Organelles replicate and final
preparations for division.
Mitosis
Division of the nucleus
 4-phases

Prophase
 Metaphase
 Anaphase
 Telophase

PMAT
Parts of Mitosis
Prophase

The chromatin
condense to form
visible chromosomes

The nuclear envelope
begins to dissolve

The centrioles divide
and begin to migrate
to opposite sides of
the cell
Parts of Mitosis Cont…
Metaphase

Centrioles have
moved to opposite
sides of the cell

The spindle has
formed

Chromosomes are
lined up in the middle
of the cell across the
equator
Parts of Mitosis Cont…
Anaphase

The centromeres split
and the spindles pull
the sister chromatids
apart toward opposite
sides of the cell
Parts of Mitosis Cont…
Telophase

The chromosomes
move to opposite
sides of the cell.

The nuclear envelope
begins to reform
around each set of
chromosomes at
opposite sides of the
cell.
Cytokinesis



Division of the
cytoplasm
Begins to occur
during telophase
Different in plants and
animal cells
Cytokinesis Cont…

Animal cells: the plasma membrane
pinches in to form two separate cells

Plant cells: A rigid cell plate begins to form
between the two new cells, dividing them
and becoming a cell wall.
mitosis animation
Control of the Cell Cycle

The cell cycle is controlled by proteins and
enzymes
Contact with other cells causes cell to stop
dividing.
 Cell stop dividing when they lose contact
with other cells

Cancer

Uncontrolled cell growth resulting in
tumors

Metastasis: Cells break lose and travel
through the circulatory system spreading
throughout the body.
Causes of Cancer

Environmental factors that damage genes.

Ex: Cigarette smoke, UV rays from the sun,
air and water pollution, viruses