CELLS & Heredity
Cells-the basic units of all living things
Cell Theory1.
All organisms are made of cells
2.
All cells come from existing cells
3.
Cells are the basic units of all living
things
Microscopes
Total magnification=
eyepiece magnification X objective
example: If the eyepiece=10X and
objective=40X, then
total magnification=10 x 40=400X
So, the object you are looking at appears
400 times larger
Cell Parts-
1.
Cell membrane-thin layer that holds
cell together
2.
Cell wall-protects and supports
plant cells only
3.
Nucleus-control center; DNA is
here
4.
Mitochondria-powers the cell,
releases energy from food
5.
Ribosomes-makes proteins
6.
Lysosomes-break down food,
digests waste
7.
Golgi-packages materials
8.
Endoplasmic Reticulum (ER)-
carries materials around the cell
Cell membrane-selectively permeable
(allows some things to pass through it)
*Allows-water, oxygen, carbon dioxide
*Stops or limits-sugars and salts
No energy is needed for:
Diffusion-movement from higher to
lower concentration
Osmosis-diffusion of water
Active transport-movement through
membrane that requires energy, from
low to high concentration
Photosynthesis-process by which plant
cells capture light energy to make food
Carbon dioxide + water + lightoxygen +
sugar (glucose)
Chlorophyll-green pigment in plants that
absorb light
Most leaves are flat and wide so they can
absorb more light energy.
Almost all organisms get their energy
directly or indirectly from the sun.
Plants get it directly; others get it from
eating plants or animals
Respiration-In animals, cells use glucose
for energy
Oxygen + glucosewater + carbon
dioxide + energy
Photosynthesis can be thought of as the
opposite of respiration.
Bacterial Cells-has cell wall &
membrane, but no nucleus
Some cause disease, but many are
helpful (digestion)
Chromosome: in the nucleus, contains
DNA (determine traits)
Trait: characteristic of an organism
(color, shape, etc)
Asexual Reproduction- one parent cell
splits to make 2 new cells (offspring);
offspring will have the exact same DNA
as the parent
Types of Asexual
1.Mitosis: when a plant grows or when
your body makes new blood, skin, or
hair cells
2.Fission: cells without a nucleus
(bacteria) make 2 identical copies
3. Regeneration: part of an organism
breaks off and it grows back (starfish)
For asexual, if a parent cell has 21
chromosomes, all offspring cells will
have 21
Sexual Reproduction-requires 2 parents
Female sex cell=egg
male=sperm
Sperm fertilizes the egg
Meiosis: sexual reproduction where (for
humans):
1.
The egg and sperm’s 23
chromosomes combine to make a
zygote, which has 46
2.
This gives offspring traits from
each parent
**What are the advantages of asexual
reproduction?
1.
No mate is needed, so more
offspring produced
2.
Faster
3.
Less chance for mutations (genetic
mistakes)
Disadvantage?
Since offspring is identical to parent,
there are no variations, they can’t adapt
**What is the advantage of sexual
reproduction?
Genes from 2 parents make
adaptation easier
Disadvantages ?
1.
A mate is needed
2.
Males can’t reproduce
3.
Mutations are possible
Specialized Cells-cells
that combine to form tissue (muscle
cells form muscle)
1. Similar cells combine to make
tissue
2. Similar tissues combine to make an
organ
3. Organs that work together make an
organ system
4. Organ systems work together to
make an organism
Heredity-passing of traits from parents to
offspring
Genetics-the study of how traits are
passed
Gene-basic unit of inheritance, passed
from parents to offspring, determines
traits
Trait-characteristic or feature of an
organism (eye color)
DNA-chemical in nucleus that contains
the code that tells an organism how to
grow and function (looks like a twisted
ladder, contains proteins)
Alleles-different forms of traits that make
up a gene pair; represented by upper and
lower case letters
Gregor Mendel’s Pea Plant Experiment
(1800’s)
Dominant: form of a trait that shows
and prevents the Recessive form from
being seen
For pea plantsTall is dominant and
short is recessive
T=Tall
t=short
(these are the alleles
for height)
Homozygous (Purebred)=TT or tt
Heterozygous (Hybrid)=Tt
Genotypes are the letters (TT, Tt, tt)
Phenotypes are the traits (Tall, short)
Pedigree Chart- diagram that shows the
phenotypes of a gene and its ancestors
from one generation to the next (filled
in means they have the trait)
This example is for Righthandedness
(dominant) and Lefthandedness (rec.)
Conclusion for Toothpick Fish Activity:
Green adapted to be dominant because it
was camouflaged by algae. When the
river was polluted, algae died and green
fish were easy prey. Eventually, another
color will become dominant!
People from different parts of the world
can still be so much alike genetically
that they can use blood or organs from
another person.
BUT, people from one area can be
different in their skin color, size and
personality because of genetics, their
surroundings, nutrition, or how they are
raised.