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BIOLOGY
CHAPTER 4, 5, 6, 23, 25,
Chapter 4
Helps the
cell/organism
to maintain
internal
environment

4
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2
WATER
-Aquaporin’s-allow water to quickly cross the membrane
-Channel protein-forms pore through membrane-allow
molecules to pass
-Vesicle Formation-another way molecule can exit
(exocytosis) or enter a cell (endocytosis)
-Diffusion- move of molecules from high to low concentration


Influences: temperature, pressure, electrical currents,
and molecule size

-Solute-solution contains solid
-Solvent-solution contains liquid
-Osmotic pressure-develops in a system-osmosis-greater the
pressure- water will diffuse into that direction
4
...
3



Eukaryotic
Haploid
Chromosomes
Composed of
Chromatincombination of
both DNA and
protein

Half the
diploid
number
One of each
kind of
chromosome

Centromere Sister
Chromatids
Duplicated
chromosome is
composed of
two sister
chromatids
held together

Identical DNA
sequence

MITOSIS-OCCURS WHEN
TISSUES GROW OR WHEN
REPAIR OCCURS
Daughter Chromosomesdivide sister chromatids

Prophase
Centrosomes began
moving away from
each other
Nucleolus begins to
disappear, chromatin
and chromosomes
are now visible
Spindle begins
forming late

Metaphase

Anaphase

Telophase

Fully formed spindle
consists of poles
Chromosomes attach
to centromere spindle
fibers

Centromere unite
Sister chromatids
divide
Daughter
chromosomes move
toward the opposite
pole

Spindle disappears
Daughter nucleus
contain the same
number of
chromosomes
Chromosomes
became more diffuse
again

Cytokinesis-separate processes of mitosis
Cleavage furrow-membrane between two daughter nuclei begins to
form-contractile ring-band of actin filaments-pulling a string on a balloon

Homologous
Chromosome
come
together lie
side by side
Produces four
Most the time in
daughter nuclei
all tissues during
and following
growth and repair
cytokinesis
Haploid and
half
chromosome
number-same
number as
parent cell

Centromeres split and sister
chromatids-daughter
chromosomes move to
opposite poles during
anaphase

Meiosis-involves sexual
reproduction, reduces
chromosome number

Sexually reproducing organism

MITOSIS

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2
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Cellular metabolism-sum of all chemical reactions that occur in cell
Catabolism-breaking down molecules
Anabolism-building up molecules
Reactants-substances that participate in a reaction
Products-substances that form as a result of a reaction
Free energy-cell biologist use instead-amount of energy available
Exergonic reactions-spontaneous and release energy
Endergonic reactions-require an input of energy to occur
ATP-commom energy currency of cells-used in many different types of reactions-high energyenergy stored in chemical bonds of phosphates
Coupled reactions-energy released by an exergonic reaction
ATP can be used for the following
-Chemical work:atp supplies the energy need to synthesize anabolism that make up the cell
-Transport work-atp supplies the energy need to pump substances across the plasma
membrane
-Mechanical work-atp supplies the energy need to permit muscles to contract
6
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1
Frederick Griffth-late 1920’s-attempting to develop a vaccine against a form of bacteria-causes
pneumonia in mammals
1931- experiment with bacteria- Smooth strain bacteria and Rough strain bacteria

Mouse

Mouse

S Strain and
Capsule

R Strain and S Strain
without capsule

Died

Did not Died

Frederick Griffth
S strain and R strain

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

1940-genes are on chromosomes-contain both proteins and nucleic acids
Protein-contain up to 20 different amino acids
DNA is Genetic material
Oswald Avery, Colin MacLeod, Maclyn
McCarty (1944)

Alfred Hershey and Martha Chase (1950)

A
...
)
DNase-enzyme digests DNAprevents transforming-supports DNA
genetic material
C
...
)
Enzymes has no effect on
transforming substance

-radioactive tracers-in bacteria cellsbecome transformed

Double Helix
-James Watson and Francis Crick discovered (1950)
- DNA-chain of nucleotides-deoxyribose, phosphate,
and nitrogen containing base-purines (double ring),
pyrimidines (single ring)
-strands held together by hydrogen
- Complementary base pairing- hydrogen bonding
25
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3

Messenger
RNA

Definition

Relies

Requires

Translation

Transcription

Process using
genetic sequence
to synthesize
protein

On different RNA
molecules

Translation

The Genetic
Code

Gene

Transcription

-codon-three
base sequence in
messenger RNA

Messenger RNAcarry info to
DNA-protein
synthesis

- stop codons
(UAA, UGA,
UAG)

Processing of
mRNA (exons
and introns)

Transfer RNA
- anticodonthree base-pairs
with MRNA
codon
Initiation
- brings all the
translation
components
together
Elongation
- is the protein
synthesis step in
which a
polypeptide
increases in
length one
amino acid at a
time
Termination
- is the final step
in protein
synthesis

Translation
and
Transcription

Translation- the
sequence of
mRNA basesdetermines the
sequence of

amino acids in a
polypeptide
Transcription- a
portion of DNA
serves as a
template for
mRNA formation

Summary

mRNA-carries
info to the DNA

RNA-composed
of ribosomes

25
...

-Control: pretranscriptional control,
transcriptional control,
posttranscriptional control,
translational control, and
posttranslational control
...

-Female has two chromosomes and male has one
Transcriptional Control

Posttranscriptional Control

-each gene has its own promoter

-messenger RNA (mRNA) is processed before it
leaves the nucleus and passes into the cytoplasm
...


-transcription activators are proteins that speed
transcription dramatically
...
5

Gene Mutation
-permanent change in the sequence of bases
in DNA

Causes of Mutation

-Germ line mutations-sex linked- can cause
cancer
Causes of Mutation
-Error replication-very rare-mismatched pairs
are then replaced with the correct
nucleotides
-Mutagens-environmental influencesradioactive and certain organic chemicals
-Transposons- DNA sequences-movement
new location sometimes alter genes –
jumping genes- Barbara McClintock

Effect of Mutations on Protein Activity
-change in a single DNA nucleotide and specific
amino acids
-Sickle-shaped cells clog blood vessels and die off
more quickly than normal-shaped cells
...
(deleted c from cat so it be at)

Evolution
-Charles Darwism
-species arise and change
over time due to nature
-explains how we share
common ancestor,
diversity of life, and how
species adapt
-heritable adaption occurs

-

Inheritance of acquired
characteristics
-Jean-Baptiste de Lamarck
-environment can bring
about inherited change

25
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3

MICROEVOLUTION
-traits can change temporary-environment-Darwin
-Environment-genes interact-determine traits
-Definition-evolutionary change within populations
-Population genetics-field of biology that studies diversity of
population of gene-interest how populations evolve over
generation

Five Agents of Evolutionary Change
Mutations

Genetic Drift

-Hardy-Weinberg equilibrium-new mutations-cause
allele frequencies in population to change

-changes in allele frequencies of gene poolrandom meeting of gametes during fertilization

-genetic changes

-Greater effects in small population-few gametes
to assort

-recognize as random events
-some can cause bacteria resistance to antibiotics

-Removal of gametes-random event- effect allele
frequencies in the next generation

-some can harm

-Bottleneck Effect-a natural disaster that kills
large population

-point mutation-change in a single nucleotide in a genesilent

-Founder Effect-few individual form new colony

Genetic Flow
-Movement of alleles among population-or gametes
migrate from one population to another- breed new
population

Nonrandom Mating
-individuals selection when chose mate with
preferred trait
-Inbreeding-change genotype frequencies-dwarfism
- mating between close relatives

Natural Selection
-Individual variation-member of population differ
from one another
-Inheritance-heritable genetic differences
-Overproduction-struggle for existence-produce
more offspring than the environment can support
-Differential reproductive success-better adapted to
environment produce more offspring
-Fitness-individual measured by number of fertile
offspring produced in a lifetime

Stabilizing Selection
-extreme phenotypes

selected against
-improve adaption of
population
-human birth weight

-extreme phenotype favored

-reduces variability in
birth weight in human
population

-shifts can occur-population
adapting to changing environment
-Equus-change environment from
forest conditions to grassland

-Systematic Biology-the study of the
evolutionary history of biodiversity

-Hyracotherium-modern horseadapted to forestlike environmentviewed straight line of descentmany sides became extinct

-Taxonomy-branch of systematic biology
concerned with identifying, naming, and
classifying organisms
-Classification-process of naming and
assigning organisms or groups to taxon
-Phylogenetic-branch of systematic
biology studies the evolutionary
relatedness among groups of organisms
-Phylogeny-evolutionary history of group
of organisms

Directional Selection
Classification

Macroevolution and Speciation
-history of life on Earth-Macroevolution
-Speciation-splitting of one species into
two or more species-macroevolution
involves
-Result-micro-evolutionary changeformation of new species
-Species-group of organisms that are
capable of inbreeding
-different species do not exchange
genes

Prezygotic isolation mechanisms

Postzygotic isolating mechanisms

-Prezygotic isolation mechanismsbefore fertilization and reproduction
never attempted
-Postzygotic isolating mechanismsafter fertilization, reproduction may
take place, does not produce fertile
offspring
-Speciation-when ones species gives
rise to two species
-Allopatric speciation-population
becomes separated by geographic
barrier and gene flow no longer
possible
-Adaptive radiation-rapid evolution of
several species from a common
ancestor into new areas

Adaptive Radiation



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