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Genetics unit study guide
Vocabulary:
11.1
11.2
11.3
12.2
12.3
12.4
asexual vs. sexual reproduction
gamete vs. somatic cells
zygote
fertilization
diploid vs. haploid
homologous chromosomes
sex chromosome vs. autosome
meiosis vs. mitosis
crossing-over
independent assortment
sperm vs. egg (ovum)
allele
dominant vs. recessive
genotype vs. phenotype
homozygous vs. heterozygous
testcross
polygenic character
13.1
13.2
13.3
14.1
15.2
15.3
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DNA vs. gene vs. chromosome
nucleotide (and its 3 parts)
nitrogen base (adenine, guanine, cytosine,
guanine, uracil (13.2))
double helix
replication
transcription vs. translation
ribose vs. deoxyribose
messenger vs. transfer vs. ribosomal RNA
codon
mutation (point vs. insertion vs. deletion)
mutagen
nondisjunction
genetic engineering
recombinant DNA
plasmid (also in 14.3)
restriction enzyme
Textbook sections:
11.1 – Methods of producing new organisms
--in asexual reproduction, _____ parent(s) transfer(s) DNA to the offspring, so the offspring is
genetically (identical / different) than the parent(s)
--in sexual reproduction, _____ parent(s) transfer(s) DNA to the offspring, so the offspring is
genetically (identical / different) than the parent(s)
--some organisms can do both (not humans!) … so why would an organism choose to
reproduce asexually (what are its advantages?)
why would an organism choose to reproduce sexually (what are its advantages?)
--complete the blanks below with the words gene, chromosome, and DNA
___________ contains the code for making proteins. A small part of this sequence that
codes for one specific protein is called a _________, and all of this can be packed up into
a larger structure called a ____________.
--chromosomes come in pairs … these pairs contain the same genes (though they might have
slightly different versions) … I am showing three genes below on the pair of chromosomes
A
a
r
r
Because these two chromosomes both contain the “A”
gene, “R” gene, and “G” gene, the chromosomes are a
pair, called
G
G
___________________ chromosomes.
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--different species have different numbers of chromosomes – humans have ______ total
chromosomes in every body cell (or __________ cell) … or _____ pairs of homologous
chromosomes … these cells have paired chromosomes, so we call these cells (diploid / haploid)
--of those chromosomes, one pair has genes that determine whether the human will be
male or female … we call this pair the ____________________
--males have _______ chromosomes, females have ________ chromosomes
--the other chromosomes have genes that do NOT determine male / female sex, so we call
them _____________
--in reproduction, the goal is to deliver a copy of each pair of chromosomes (and the right
number of chromosomes) to the offspring
--asexual: parent produces a cell with all chromosomes for offspring (starting cell diploid
 ending cell diploid)
--what type of cell division does this involve in eukaryotes? _______________
--what type of cell division does this involve in prokaryotes (see ch. 10)?
______________ ______________
--sexual: each parent produces cells that have half the chromosomes in them (starting
cell diploid  ending cell _____________)
--reproduction occurs when sex cells (also called _____________) combine in an
event called ____________________, now offspring has diploid cell again
--what type of cell division produces haploid cells? see section 11.2 below
11.2 – Producing haploid cells, producing genetic variety
Start: one diploid body cell (or germ cell)
End: ___ ____________ _______________
(#) (haploid / diploid) (type of cell)
Steps: look at the picture on p. 250-251
a) Duplicate chromosomes in interphase to make Xs
b) Meiosis I – splitting up _______________________ (keep the Xs intact)
c) Meiosis II – splitting up _______________________ (same as mitosis, review 10.2)
Meiosis
Purpose (in humans)
Location of cell
division (in humans)
# cells produced
# chromosomes in
product cells (human)
Haploid or diploid
cells produced?
Mitosis (review 10.2)
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--Meiosis generates genetic variation in offspring
--when lining up in meiosis I, the inner tips of the X pairs can switch with each other,
called ____________________
--when lining up, the pairs of Xs can line up 2 different ways every time gametes are
made – also, each pair of Xs lines up independently of each other … this is
called ____________________________ (look at figure 6, p. 254)
11.3 – The role of mitosis and meiosis in an overall life cycle
--be able to fill in the proper terms for the human life cycle (see next page), skim p. 258 and
alternate life cycles (we will study these more next semester)
human adult body cells
Process: ____________
Type of cell:
______________
Circle:
haploid / diploid
Circle:
haploid / diploid
Process: ____________
Process: ____________
Type of cell
Circle:
general: ____________ haploid / diploid
male: ___________
female: __________
12.1, 12.2 and 12.3 – Mendel’s genetics (and Punnett squares)
You can omit pedigree analysis section on pages 280-281 in section 12.3
--Mendel studied ______ _______ to understand the principles of genetics
This plant is an excellent model for studying heredity—why?
a)
b)
c)
--Mendel knew nothing about DNA, proteins, chromosomes, or meiosis … but still discovered
some basic principles about that can be explained with meiosis above
--Mendel’s conclusions:
1) Pea plants have two copies of every trait
connection to meiosis?
2) When reproducing offspring, these two copies separate – the offspring only gets one copy of
the trait from each parent = Mendel’s law of _________________
connection to meiosis?
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3) Some traits have two possibilities – if an organism received one type of trait from each
parent, the organism will show the (dominant / recessive) trait (the other one hiding is called the
(dominant / recessive) trait)
connection to meiosis – these different possibilities are called _________. They represent slight
differences in DNA coding that make slightly different proteins
Connected with the above statement, an organism’s genotype is different from its phenotype
(make sure you understand the difference)
T = tall allele
t = short allele
Genotype possibilities: TT (called __________ ___________ generally)
Tt (called _______________ generally)
tt (called __________ ___________ generally)
Phenotype possibilities: tall or short
--Mendel was able to tell the difference between TT tall and Tt tall plants (even though they
looked identically tall). How could he tell them apart using a test cross? (p. 277 quicklab)
(show Punnett squares
and explain results)
5) Traits are independent of each other – whether a plant is tall or short does not affect the odds
of producing offspring with green or yellow seeds = Mendel’s law of ________________
connection to meiosis? (assuming two genes are on different chromosomes)
--Be able to set up and analyze a one trait Punnett square
a) Convert words to parent genotypes
c) Convert offspring genotypes into words
b) Create and fill in Punnett square
d) Calculate simple probabilities
--Be able to set up a dihybrid Punnett square showing the different gametes that each parent
could create
--for example, cross a PpYy parent with a PPYy parent
--name 4 different gametes made by PpYy parent? _____, _____, _____, _____
--name 2 different gametes made by PPYy parent? _____, _____
12.4 – Beyond pea plants: non-Mendelian genetics
Assumptions in Mendel’s pea-plant genetics often are not valid in more complex organisms
1) Assumption: Only one gene controls the trait we are talking about
Exception: Multiple genes influence an overall trait, called ____________ _____________
(example: _______________)
2) Assumption: One allele completely dominates the other
Exception: a) Incomplete dominance –
b) Codominance –
3) Assumption: There are only two possibilities for one gene (tall or short, yellow or green)
Exception: Multiple alleles (example: _________________)
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4) Assumption: Only genes influence traits
Exception: Environmental factors may play a role in the overall phenotype of an organism
5) Assumption: Genes are inherited independently because they are on different chromosomes
Exception: ________ genes are inherited together because they are on the same chromosome
13.1 – Structure of DNA
--Recall the function of DNA (cell unit)
--DNA is built from lots of _____________ combining together
--Each unit is made of three parts: a ___________, _________, and ___________
--In DNA, there are four possible bases that make up the code (often abbreviated as one letter):
_________ (__), _________ (__), _________(__), and _________.(__)
_________ (__) pairs with _________ (__)
_________ (__) pairs with _________ (__)
--What bond forms between the above bases? ____________ bonds which are (weak / strong)
--These components come together to give DNA the overall shape of a _________ _________.
13.2 – How the cell makes a copy of the DNA code
--Copying the DNA instructions is called DNA _______________
--Recall when the cell needs to make a copy of DNA (during cell division, including both
______________ and _____________)
--Explain the steps of this process (illustrated p. 292-3) – draw a picture also
Step 1: _______________________________________________________
Step 2: _______________________________________________________
Step 3: _______________________________________________________
--be able to match base pairs given DNA during replication
--to prevent errors in the new code, __________ “proofread” the DNA as it is copying
--generally, (prokaryotic / eukaryotic) cells have more DNA
13.3 – Expressing a gene – building a protein using transcription and translation
--Reminder – what are proteins built from? __________ __________
--What small organelle is in charge of protein construction? ______________
--RNA – takes message in between DNA (in nucleus) and the ribosome (in cytoplasm)
--RNA is a nucleic acid, but different from DNA in 3 ways:
1) The sugar that makes up RNA’s nucleotides is called _________, whereas
DNA’s sugar is called ________________
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2) RNA is (single / double) stranded, while DNA is (single / double) stranded
3) RNA has one different nitrogen base: instead of _________(__) (in
DNA), RNA uses _________ (__) to pair with _________ (__) on DNA
Building a protein:
Step 1: Transcription—copying DNA instructions and bringing to the construction crew
--DNA never leaves the __________ in eukaryotes. It should be protected at all times.
(Actually, one time in the cell unit DNA left the nucleus … when?)
overview:--mRNA (the m stands for _________) reads the DNA inside the _________
and brings the message out into the _________ where the ribosomes are located
Step 1: Enzymes unzip DNA by breaking the _________ _________ between bases
Step 2: RNA nucleotides match up with one of the DNA strands
Step 3: Single RNA strand leaves nucleus, DNA strands reconnect (and stay in nucleus)
--be able to match mRNA base pairs given a sample strand of DNA (p.296)
Step 2: Translation—reading the instructions and building protein (takes place where again?)
--three different components coming together:
1) mRNA – carries instructions from DNA
2) rRNA – (r stands for _________) – what’s its job?
3) tRNA – (t stands for _________) – what’s its job?
--mRNA’s code is read in groups of _____ (number) letters at a time – this group is
called a __________ on mRNA
Step 1: rRNA in ribosome binds to mRNA
Step 2: 1st tRNA binds to mRNA start codon and attaches 1st amino acid
Step 3: 2nd tRNA binds to mRNA and attaches 2nd amino acid
Step 4: 3rd tRNA binds to mRNA and attaches 3rd amino acid
[…] (tens or hundreds of amino acids continue to be added)
Step 5: Final tRNA binds and “cuts” the string of amino acids away from the ribosome –
amino acids go on to fold up into proper protein shape
--(from cell unit) – proteins may also go on to the ______________
____________ in eukaryotes, where proteins are modified some more
--Be able to match mRNA codons with amino acids (p. 307 chart will be available during test)
--(not in book) I just want you to appreciate that ALL your body cells have the same DNA (after
all, they were created by mitosis) … so they have different functions because each cell
expresses different genes within the overall code
14.1 – Mutation
--what is a mutation?
--mutations are NOT always harmful … they can no effect, or even be helpful
--_________ are environmental factors that can cause mutations
--2 major categories include _________ and _________
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--If mutations occur in _________ cells, then the effects could be passed on to future offspring.
--if mutations occur in genes which code for proteins that control the cell cycle, then
_________ can result
--Some types of mutations:
--point mutation— _____________________________________________
--could be a silent mutation, which means what?
--could change one amino acid in protein
--frameshift mutation – _________________________________________
--could involve additions OR deletions to DNA code
--why does this usually cause more of a change in protein than point mutation?
--Errors can occur in meiosis, and create gametes with too many or not enough chromosomes
--the failure to separate chromosomes is called ___________________
--name one example of a disorder caused by this problem
Omit ALL 14.2 and 14.3
15.1 – Human genome
--read p. 345 & p. 348 for current findings and future genetic research (you can omit p. 346-7)
15.2 and 15.3 – Selected examples of genetic engineering (omit other pages in sections)
--read “manipulating genes” section p. 350 and 351 (omit “manipulating cell interactions”
--read “ethical and social issues” p. 354
--read p. 360 for a method of achieving genetic engineering using restriction enzymes, bacterial
plasmids, and an antibiotic screen
--explain the role of restriction enzymes
--explain the role of bacterial plasmids
--explain the role of the antibiotic