Final exam study guide

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What is the hierarchy of Life?
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Prokaryotic vs. eukaryotic cells
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Plant vs. animal cells
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What is a hypothesis?
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What are the steps of the scientific method?
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What is the structure of an atom?
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What are the four biological macromolecules and
what they are composed of?
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In order of increasing complexity: atoms
elements
molecules/compounds organelle
cell tissues organ organ system organism
population community ecosystem
biosphere
A prokaryotic cell lacks membrane bound
organelles, is smaller than most cells of the body
(0-10 micrometers) and has DNA as its genetic
material that is not surrounded by a nuclear
membrane
A eukaryotic cell has a nuclear membrane around
its DNA and other membrane bound organelles,
is larger than prokaryotic cells (10-100
micrometers)
Although these differences exist, prokaryotic and
eukaryotic cells use their DNA to make proteins
Plant cells have most of the same organelles as
animal cells except plant cells have cell walls
(made of cellulose, exterior to their plasma
membrane), a central vacuole and chloroplasts
Animal cells have exclusive structures like
centrioles, flagella and lysosomes
A hypothesis is a possible answer to some
question. It is phrased as a statement and should
be testable and falsifiable.
Observation, question, hypothesis, prediction,
test, conclude,
The atomic nucleus (towards center) contains
protons (+) and neutrons (neutral) while the
electrons (-) orbit around the atomic nucleus
Carbohydrates ( composed of monosaccharides)
Proteins ( composed of amino acids)
Lipids (TG’s are composed of a glycerol backbone
and 3 fatty acid chains); there are also steroids
and phospholipids (found in cell membranes)
Nucleic Acids (composed of nucleotides; each
nucleotide consist of a sugar, phosphate and
nitrogen base
Know the function of the following organelles:
o Nucleus
o Plasma membrane
o Endoplasmic reticulum (Smooth
and rough); ribosomes
o Golgi
o Lysosome
o Mitochondria & chloroplast
1
What does semi-permeable mean as it relates to
the plasma membrane of cells?
Plasma membranes let some things cross easily
and other substances cannot. Because the plasma
membrane is mainly composed of phospholipids, it
will allow small lipids to cross directly through the
plasma membrane, while larger, polar, hydrophilic
substances cannot cross easily and use a transport
protein to cross instead.
What is active transport? Passive transport?
Active transport is transport that moves
substances against their concentration gradient
(from low to high) using energy (ATP)
Passive transport moves substances down (from
high to low) their concentration gradient without
using any ATP
A concentration gradient is when you have more
of one substance in one place and less of it in
another and these locations are separated by
some distance.
What type of macromolecule is an enzyme?
Enzymes are proteins
What is the function of an enzyme?
Enzymes function by lowering the activation
energy of a reaction, therefore, they are biological
catalysts, acting to speed up the rate of chemical
reactions.
Be able to define cellular respiration. What is the
purpose of this cellular respiration?
Cellular respiration is the oxidation of an organic
fuel source (usually carbohydrate) to form ATP,
carbon dioxide and water. The fuel source
(carbohydrate) is oxidized forming carbon dioxide
and oxygen is reduced forming water. The
chemical energy in food is stored in ATP and ATP
powers cellular activities
What are the three stages of cellular (aerobic)
respiration?
The three stages of (cellular) aerobic respiration
are 1) Glycolysis 2) Kreb’s cycle 3) The Electron
transport chain (oxidative phosphorylation)
2
What is photosynthesis?
Photosynthesis is when solar energy is used to
produce ATP, sugar and oxygen. In photosynthesis,
water is oxidized to produce oxygen while carbon
dioxide is reduced to produce sugar.
What types of organisms do photosynthesis?
Photoautotrophs are the organisms that can use
solar energy and inorganic substances like water
and CO2 to make organic substances like glucose
and ATP.
What organelle must be present in a cell to carry
out photosynthesis?
In order to carry out photosynthesis, a cell must
contain chloroplasts.
How are cellular respiration and photosynthesis
connected?
They are connected because the products of
photosynthesis (oxygen and glucose) are the
reactants for cellular respiration and vise versa.
What is DNA? What is the function of DNA? What
is the structure of DNA?
DNA is the genetic and hereditary material. The
function of DNA is to carry information for the
synthesis of proteins. DNA resembles a twisted
rope latter, where it consists of two polynucleotide
strands mad of alternating sugars and phosphates,
with the nitrogen bases toward the center of the
“ladder”
How are the following related to DNA?
Antiparallel
Polynucleotide strands
Hydrogen bonds
Complementary
Antiparallel refers to the fact that the two
polynucleotide strands run in opposite directions.
Hydrogen bonds hold the nitrogen bases together
in the center of the molecule.
Complementary refers to the specific base pairing
that occurs between A and T and G and C bases. So
if you know what the sequence of bases are on
one strand you can predict the sequence of bases
on the “complementary” strand based on these
base pairing rules. *Because RNA lacks thymine
and has uracil instead, A base pairs with U (uracil).
3
What are differences between mitosis and
meiosis?
Mitosis is asexual reproduction where one cell
divides into two identical daughter cells. Mitosis
occurs in somatic cells during the mitotic phase of
the cell cycle. The parent cell copies its DNA once
and divides once in mitosis.
Meiosis is the production of gametes and occurs in
male and female sex organs (testes and ovaries). In
meiosis a diploid nucleus is converted to a haploid
nucleus. Meiosis reduces the chromosome number
by half so that the four gametes that are produced
have only half of the DNA as the diploid cell that
they came from.
The cell copies its DNA once and divides twice in
meiosis
What is a somatic cell vs. a sex cell?
A somatic cell is a body cell and a sex cell is a
gamete (sperm and egg). When a somatic cell
undergoes mitosis it produces 2 identical daughter
cells, each with the same amount of type of DNA.
When a somatic cell undergoes meiosis, it
produces 4 unique daughter cells, each with half of
the amount of DNA as the parent cell.
A sex cell is a gamete (male gamete = sperm;
female gamete = egg or ovum)
What are alleles? (pg. 187)
Alleles are alternate forms of a gene, one form
from Mom and one form from Dad. At least two
alleles exist for a gene. Alleles of a given gene are
located in the same locus along homologous
chromosomes.
4
Dominant allele?
A dominant allele masks the recessive allele. In the
heterozygote with two different alleles, if one is
dominant and one is recessive, the dominant allele
will determine the phenotype.
Ex. A is dominant and codes for purple flower
color; a is recessive and codes for white flower
color. If a plant is heterozygous for flower color it
has the Aa genotype and its phenotype is purple,
the trait that is coded for by the dominant allele.
Recessive allele?
The recessive allele is completely masked by the
dominant allele, therefore, in the example above a
plant would have to be aa, lacking the dominant
allele, in order to have a white phenotype.
What is a genetic cross? (pg. 186)
A genetic cross, shows the possible combinations
of gametes and the resulting four possible
offspring.
Monohybrid cross?
A monohybrid cross follows just one character like
flower color.
What is diploid?
Diploid (2n) refers to having two sets of DNA (one
set from Mom one set from Dad). In human
somatic cells there are a total of 46 chromosomes
that arranged into 23 homologous pairs. We
receive 23 chromosomes from Mom and 23
chromosomes from Dad.
Haploid?
Haploid (n) refers to having one set of DNA.
Haploid nuclei are in gametes, where there is only
half of the DNA as compared to the rest of the
somatic cells of the body. Haploid nuclei are
produced during Meiosis
5
What is the human diploid and haploid
number?
The human diploid number is 46, given by 2n,
where n is the haploid number 23.
What is the order of phases in the cell cycle?
IPMAT: Interphase, Prophase, Metaphase,
Anaphase, Telophase and Cytokinesis
What is the main event in each phase?
Interphase: DNA is copied
Prophase: DNA condenses into chromosomes
Metaphase: duplicated chromosomes align along
equator
Anaphase: Sister chromatids separate
Telophase & cytokinesis: chromosomes unravel,
membrane forms around chromatin, cytoplasmic
division
What is the law of segregation?
A sperm or egg carries only one allele for each
inherited character because allele pairs separate
(segregate) from each other during the production
of gametes (meiosis)
Law of Independent Assortment?
Each pair of alleles segregates independently of
other pairs of alleles during gamete formation. The
inheritance of one character (eye color) has no
effect on the inheritance of another (liver enzyme
type)
Sex chromosomes vs. autosomes
Sex chromosomes are the X or Y chromosomes
that carry information regarding sex, sexual
characteristics, etc. however they also carry
information unrelated to sex. A female has two X
sex chromosomes (XX) and a male has one Y and
one X sex chromosome (XY)
Autosomes are non-sex chromosomes
6
What is the purpose of DNA replication and what
specific part of the cell cycle does this occur in?
The purpose of DNA replication is to ensure that
all cells of the body have the same amount and
type of DNA. DNA replication takes place during
the S-phase of Interphase of the cell cycle.
What is semi-conservative DNA replication?
Semiconservative DNA replication is a model that
describes how double stranded DNA is copied
prior to cell division. This model describes how the
double strands separate as hydrogen bonds
between strands are broken and each exposed
strand acts as a template for the synthesis of a
new strand. Enzymes will add the appropriate
nucleotide base (based on base pairing rules) until
the entire DNA molecule is copied. At the end of
this process, two double helices from one are
produced. Each double helix has one parental (old)
strand and one daughter (new) strand. “Semi”
refers to half of the parental DNA being
“conserved” or saved in the two double helices
that are produced.
What is a gene?
A gene is a smaller segment of DNA that carries
the information for the synthesis of one
polypeptide.
One gene-one polypeptide theory
This theory states that the function of a gene is to
code for one polypeptide, as opposed to one
enzyme as was previously believed.
What is gene expression?
Gene expression is utilizing the DNA, which means
using DNA to make RNA and using RNA to make
proteins :DNA
RNA
protein
What are the two phases of gene expression?
Where do these processes occur for eukaryotes?
For prokaryotes?
Transcription and Translation are the two phases
of gene expression. In Eukaryotes, transcription
occurs in the nucleus and translation occurs in the
cytoplasm and in prokaryotes these processes
occur together in the cytoplasm.
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What is gene regulation?
Gene regulation is turning genes on or off,
speeding up the transcription of genes or slowing
down the transcription of genes.
Genes are regulated by proteins in both
prokaryotes and eukaryotes.
Some cells use methylation (adding a CH3) group
to DNA) to prevent genes from being transcribed,
therefore preventing the expression of this gene.
How is the genetic code written in the DNA?
What is the genetic code? (pg. 226)
In terms of structure and organization, how is the
genetic material different in prokaryotic versus a
eukaryotic cell?
The information to make proteins is written in the
DNA as three-letter “words” or triplets. Triplets
will determine the three-base sequences in mRNA
called codons. Each codon specifies a particular
amino acid.
The genetic code refers to the 64 possible codons
that exist.
In prokaryotic cells, their DNA is not enclosed in a
membrane and they have one single, circular
chromosome. Their genes are arranged into
operons.
An operon consists of a promoter, an operator and
related genes. The lactose operon of E.coli had the
Promoter, operator and 3 lactose utilization genes
In eukaryotic cells the DNA is linear and each gene
has a promoter, then the gene then a terminator
sequence. The eukaryotic genome is much larger
than that of a prokaryote.
8
What molecules do prokaryotic and eukaryotic
cells use to regulate gene expression?
Prokaryotes and Eukaryotes use Proteins to
regulate their DNA. For example prokaryotes use
repressors and eukaryotes use transcription
factors. In both cases these proteins bind to DNA
and either inhibit or promote transcription.
In both cell types RNA polymerase binds to the
promoter.
What are the levels of regulation for eukaryotic
gene expression? (pg. 255)

Although I said seven levels, don’t worry
about this number, as long as you are
aware that there are multiple regulation
points, that is the important idea!
1)DNA unpacking- if DNA is tightly coiled, then
RNA polymerase or other necessary transcription
factors cannot access DNA to begin transcription,
therefore, no gene expression
2)RNA processing-Exons are spliced together and
introns removed; if the cap and tail are not added
to mRNA, it cannot flow through the nuclear
membrane out to the cytoplasm, or stay intact to
ensure gene expression
3) Once mRNA reaches the cytoplasm, translation
can be regulated by use of microRNAs to prevent
translation or causing the breakdown of mRNA. In
either case if mRNA is broken down, no gene
expression
4) After translation the new polypeptide must be
activated in order to be functional. If this
activation does not occur, then no gene
expression.
5) Even after proteins are activated, if they are
broken down (possibly by an enzyme), then no
gene expression
What is cloning?
Cloning is when identical cells are produced from
one. It is the same as asexual reproduction.
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Reproductive cloning uses nuclear transplantation
to produce a ball of cells (blastocyst) which can
then be placed in the uterus of a surrogate. The
offspring will carry the genetic information of the
donor nucleus and not the surrogate.
In therapeutic cloning, the goal is to produce
embryonic stem cells. These cells are removed
from the blastocyst and then through the addition
of certain chemicals and hormones, are induced to
develop in different directions, forming different
cells that can be used for therapeutic reasons.
What is the genetic basis of cancer?
The genetic basis of cancer is that we all carry
proto-oncogenes that are normal healthy genes
that code for proteins that control cell division. If a
mutation occurs within a proto-oncogene it is
converted to an oncogene which now codes for
proteins that will cause cells to grow and divide
uncontrollably. This rapid overgrowth of cells is a
tumor.
What is Hardy-Weinberg equilibrium?
The Hardy-Weinberg equation can test whether a
population is evolving. The Hardy-Weinberg
principle states that allele and genotype
frequencies will remain constant (at equilibrium) if
a population is large, mating is random, and there
is no mutation, gene flow (migration) or natural
selection.
Allele frequencies: p + q = 1
Genotype frequencies: p2 + 2pq + q2 = 1
p2 = homozygous dominant individual
2pq = heterozygotes
q2== homozygous recessive individual
10
What are the five evolutionary agents?
Evolutionary agents cause a population to evolve,
or allele frequencies to change over time. They are
mutation, migration, natural selection, small
population and selective (non-random) mating.
Although all five evolutionary agents can cause
changes in allele frequencies, Natural selection,
genetic drift, and gene flow truly cause
microevolution. Natural selection is the only
mechanism that consistently leads to adaptive
evolution. Relative fitness is the contribution an
individual makes to the gene pool of the next
generation. As a result of natural selection,
favorable traits increase in a population over time.
What is natural selection?
Natural selection is the unequal survival and
reproductive success. Individuals with traits that
make them better suited for their environment,
are more likely to live, and be able to reproduce
more than individuals with less advantageous
traits, which means that they will make a greater
contribution to the gene pool of the next
generation (unequal survival and reproductive
success)
What is the biological species concept?
The biological species concept states that
organisms are of the same species if they can
interbreed naturally and produce viable, fertile
offspring. There are several mechanisms
(allopatric, sympatric, reproductive barriers) that
can cause two separate populations to become so
genetically different that they are no longer able
to naturally produce viable and fertile offspring. If
they are no longer able to do this, they have
undergone a speciation event and are considered
different species under the biological species
concept.
How does this relate to speciation?
What is population ecology?
Population ecology studies population size and
the factors that regulate populations over time.
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Population ecologist study dispersion patterns,
interactions between biotic (living) and abiotic
(nonliving) factors in the environment.
What is a survivorship curve?
What are the three types of curves? Be able to
give an example of an animal that fits into each
curve.
A survivorship curve is formed from a plot of
survivorship (proportion of individuals from an
initial population) at various ages. There are three
types discussed in class: Type I, II and III.
Type I: shows high survivorship (low mortality) in
the early and middle ages with a decline in
survivorship in older ages. This curve is
characteristic of organisms that invest a great deal
of time and care in their young. (ex. Humans,
elephants)
Type II: shows that survivorship (or mortality) is
independent of age and that these organisms are
just as likely to die in an early age as in a later
age.(ex. Birds, rabbits, rodents)
Type III: shows that there is low survivorship (high
mortality) in the early stages of life and if these
organisms can survive until a certain age, then
they usually can survive until older age. (ex.
Marine invertebrates, sea turtles)
What are the characteristics of r-selected and Kselected organisms?
r-selected species grow rapidly in unpredictable
environments, where resources are abundant,
have a large number of offspring that develop and
reach sexual maturity rapidly, and offer little or no
parental care. K-selected species tend to be longlived animals (such as bears and elephants) that
develop slowly and produce few, but well-caredfor, offspring and maintain relatively stable
populations near carrying capacity.
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