Unit 3 Review

Unit 3 Review

By Ivana Grant

STATION 1. DNA STRUCTURE AND REPLICATION

DNA stores genetic instructions.
DNA is built from nucleotides.
Each nucleotide has:
• A sugar
• A phosphate
• A nitrogen base
A pairs with T.
C pairs with G.
Base pairing using hydrogen bonds keeps the double helix stable.

Labelling

Correctly label the nucleotide

Drag labels to their correct position on the image

phosphate

sugar (deoxyribose)

nitrogen-base

DNA

Match

Match the following DNA base pairs.

• Adenine pairs with

• Thymine pairs with

• Cytosine pairs with

• Guanine pairs with

Thymine

Adenine

Guanine

Cytosine

• Thymine

• Adenine

• Guanine

• Cytosine

Base Pairing

A bonds with T through two hydrogen bonds.
C bonds with G through three hydrogen bonds.
The order of bases forms the genetic code.
The bases on one strand decide the bases on the other strand.
Chargaff's Rule: %A = %T and %G = %C in any organism

Multiple Choice

If 35% of an organism's DNA is thymine, what is the percentage of guanine?

• 15%
• 30%
• 20%
• 25%

Multiple Choice

Which of the following are the missing data for percentage of Thymine, Guanine and Cytosine for Psyduck?

• 30%; 19%; 21%

• 19%; 30%; 21%

• 19%; 21%; 30%

• 21%; 30%; 19%

Multiple Choice

A sample of DNA is collected from an organism. It is analyzed and determined that 20% of the DNA is made up of the base adenine. Using this information, determine the amount of the three remaining bases for this sample.

• A: 25%, T: 25%, C: 25%, G: 25%
• A: 15%, T: 15%, C: 35%, G: 35%
• A: 20%, T: 20%, C: 30%, G: 30%
• A: 30%, T: 10%, C: 30%, G: 30%

Multiple Choice

Which strand is complementary to:
3’ TAC GGC ATA TTT 5’?

• 3’ ATG CCG TAT AAA 5’

• 5’ ATG CCG TAT AAA 3’

• 3’ AAC CGT TTA CCC 5’

• 5’ AAA TAG CCG TAT 3’

Match

Match the DNA sequence codon with the complimentary sequence

• ATT
• CGC
• TAC

• AGT

• CTT

TAA

GCG

ATG

TCA

GAA

• TAA
• GCG

• ATG

• TCA

• GAA

DNA Replication (Semi-Conservative)

• When: S phase of cell cycle (before cell division)

• Why: So each daughter cell gets a complete copy of DNA

• How it works:

  1. Helicase unzips/unwinds the double helix

  2. Each original strand serves as a template

  3. DNA polymerase adds complementary nucleotides

  4. Result: 2 DNA molecules, each with 1 old strand + 1 new strand

Match

Match the following: Steps of DNA Replication

• 1. Unzipping

• 2. Priming

• 3. Building and Extending

• 4. Gluing

Helicase unzips DNA helix

Primase marks starting point for DNA polymerase

DNA polymerase builds new DNA strands in 5' to 3' direction

Ligase joins DNA fragments together

• Helicase unzips DNA helix

• Primase marks starting point for DNA polymerase

• DNA polymerase builds new DNA strands in 5' to 3' direction

• Ligase joins DNA fragments together

Match

Match the following: Enzymes to Functions

• Helicase

• DNA Polymerase

• Ligase

• Primase

enzyme unzips DNA like a zipper, creating two single strands of DNA

Builder enzyme that synthesizes new strands of DNA by adding DNA nucleotides

Enzyme that joins or glues fragments of new DNA together

Enzyme that creates a starting point for DNA polymerase

• enzyme unzips DNA like a zipper, creating two single strands of DNA

• Builder enzyme that synthesizes new strands of DNA by adding DNA nucleotides

• Enzyme that joins or glues fragments of new DNA together

• Enzyme that creates a starting point for DNA polymerase

Multiple Choice

Sometimes, DNA is called "semi-conservative." Why might this be?

• The old strand is "conserved" and used to make the new strands
• Uracil is "conserved" in that it is only used to make the new strands
• ATP is "conserved" via the usage of facilitated diffusion
• Ligase is "conserved" in that it is denatured by the process

Multiple Choice

At what point in the cell cycle does DNA replication occur and why?

• Before a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions

• Before a cell divides, to provide each of the two resulting cells with an incomplete set of DNA instructions

• During cell division, to provide each of the two resulting cells with an incomplete set of DNA instructions

• After a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions

Multiple Choice

What will the matching DNA sequence be on a strand that reads AAGCTAT?

• AACGATA
• TTCGTTA
• CCTGATA
• TTCGATA

Multiple Choice

Before a cell divides, it must duplicate its DNA. Which of the following best describes DNA replication?

• The two strands separate, and an exact copy of each original strand is synthesized

• The two strands separate, and a complementary strand is synthesized from each original strand

• The two strands separate, and an exact copy of one original strand is synthesized

• The two strands separate, and a complementary strand is synthesized from one of the original strands

Multiple Choice

If a molecule was introduced that interfered with the normal function of the enzyme helicase, which of the following would be the MOST likely effect during replication?

• DNA could not unwind for replication to proceed

• Fragments of DNA could not be joined together

• New DNA nucleotides could not be added to the growing strand

• RNA primers could not be replaced with DNA nucleotides

Universal Genetic Code (SC.912.L.16.9)

• ALL organisms use the same genetic code

• The same mRNA codons code for the same amino acids in bacteria, plants, humans, etc.

• Why? Common ancestry - all life shares the same "language"

• This is why: Scientists can insert human genes into bacteria to make insulin!

• DNA has T (thymine), RNA has U (uracil)

• DNA replication makes DNA, not RNA or protein

• If given one DNA strand, write the complement using A↔T, G↔C

Multiple Choice

The genetic code is considered universal; what does this mean?

• An amino acid can be specified by more than one codon.

• Each codon codes for the same amino acid in nearly all organisms.

• Each codon corresponds to a unique amino acid.

• The sequence of bases in all organisms is the same.

Multiple Choice

What is the significance of the genetic code being universal?

• It allows for the transfer of genes between different species.

• It means that all organisms have identical DNA sequences.

• It implies that all organisms have the same number of chromosomes.

• It suggests that all organisms have the same metabolic pathways.

Multiple Choice

Why is the genetic code described as 'degenerate'?

• Because it is flawed and often leads to errors in protein synthesis.

• Because multiple codons can encode the same amino acid.

• Because it is different in every organism.

• Because it is not used by all living organisms.

Multiple Choice

Which statement BEST explains how the genetic code is universal?

• DNA sequences are unique for each species

• The nucleotide ratios in the DNA molecule are different between species

• The shape of a DNA molecule is the same in different species

• A DNA sequence codes for the same proteins in different species

Multiple Choice

Why can bacteria recognize a human gene and then produce a human protein?

• DNA replication in bacteria and humans is the same

• Bacterial cells contain the same organelles as human cells

• The basic components of DNA are the same in humans and bacteria

• Bacterial cells and human cells contain the same kind of chromosomes

Central Dogma: DNA → RNA → Protein

• TRANSCRIPTION (DNA → mRNA)

  • Where: Nucleus

  • What: DNA is copied into mRNA

  • Base pairing: A→U, T→A, G→C, C→G

  • Result: mRNA leaves nucleus and goes to ribosome

Multiple Choice

Which statement BEST describes what occurs during step 1?

• A new rRNA strand is replicated during translation.

• A new mRNA strand is produced during transcription.

• A complementary DNA strand is produced during replication.

• .A new set of amino acids are coded for by tRNA during protein formation.

Multiple Choice

Transcription goes from:

• DNA to DNA

• DNA to Protein

• DNA to RNA

• None of the above

Multiple Choice

Transcribe the DNA to RNA:

G A C - C T A - A G T

• G A C - C T A - A G T

• C U G - G A U - U C A

• C T G - G A T- T C A

Multiple Choice

What protein is UCC

• Ser

• STOP

• Thr

• Tyr

Multiple Choice

Transcribe the DNA to RNA:

A A G - C T G - T A G

• A A G - C T G - T A G

• A A G - C T G - T A G

• U U C - G A C - A U C

Multiple Choice

The "central dogma" states that genetic information flows from 

• Protein-->mRNA-->DNA
• Protein-->DNA-->mRNA
• mRNA-->DNA-->Protein
• DNA-->mRNA-->Protein

Multiple Choice

What is the result of transcription?

• The synthesis of RNA from protein

• The synthesis of protein from RNA

• The synthesis of protein from DNA

• The synthesis of RNA from DNA

Multiple Choice

RNA polymerase _____.

• links together the chain of RNA nucleotides during transcription

• creates proteins

• reads the DNA code to be transcribed

Multiple Select

Messenger RNA (mRNA) works to ____.

• codes genetic information from DNA

• conveys it to ribosomes

• duplicates DNA for mitosis

• creates proteins

Multiple Choice

How do the functions of DNA and RNA differ?

• DNA directs protein transport, while RNA aids in energy production

• DNA aids in energy production, while RNA directs protein transport

• DNA stores genetic information, while RNA transfers genetic information for protein synthesis

• DNA transfers genetic information for protein synthesis, while RNA stores genetic information

Central Dogma: DNA → RNA → Protein

• TRANSLATION (mRNA → Protein)

  • Where: Ribosome (in cytoplasm)

  • What: mRNA is read in codons (3 bases = 1 amino acid)

  • tRNA's job: Brings amino acids to the ribosome

  • Result: Chain of amino acids = protein

Multiple Choice

Which of the following identifies the process shown at point A?

• Transcription
• Replication
• Translation
• Translocation

Multiple Choice

What is the result of translation?

• The synthesis of RNA from protein

• The synthesis of protein from RNA

• The synthesis of protein from DNA

• The synthesis of RNA from DNA

Match

Match the following

• RNA Transcription

• RNA Translation

• mRNA

• tRNA

• rRNA

DNA to mRNA

mRNA code builds protein

carries code from DNA in nucleus to ribosome

brings amino acid to mRNA

part of ribosomal structure

• DNA to mRNA

• mRNA code builds protein

• carries code from DNA in nucleus to ribosome

• brings amino acid to mRNA

• part of ribosomal structure

Match

Match the following to where they occur

• nucleus

• cytoplasm

• nuclear pore

transcription

translation

mRNA leaves through

• transcription

• translation

• mRNA leaves through

Multiple Choice

If a cell suddenly stopped producing transfer RNA, which of the following processes would be immediately affected?

• mutation

• replication

• transcription

• translation

Multiple Choice

This process is called:

• Translation

• Transcription

• DNA Replication

Types of Mutations

Point or Substitution
One base is changed
Effect: Depends on whether the amino acid changes

Silent
Base changes but the amino acid stays the same
Effect: No change to the protein

Frameshift (Insertion or Deletion)
A base is added or removed
Effect: Large change. All codons after the mutation shift.

Key Points
• Mutations in gametes can pass to offspring
• Mutations in body cells do not pass to offspring
• Some mutations do not change the phenotype

Multiple Choice

What mutation has occurred here?

T-G-A-C-C-A

T-G-A-G-C-A

• Substitution

• Deletion

• Insertion

• Frameshift

Multiple Choice

ATTTGAGCC- Original

ATTGAGCC - Mutated

The example above is an example of a

• Insertion- Frameshift

• Deletion- Substitution

• Deletion -Frameshift

• All of the above

Multiple Choice

Why are insertion and deletion (frameshift) mutations so harmful?

• They change all of the codons from the mutation on down the line, which changes the amino acid sequence

• They insert things that an organism doesn't need.

• They often delete things that organisms need.

• Insertion and deletions are not any more harmful than substitution mutations.

Multiple Choice

Which mutation will cause translation to stop?

• Mutations 1 and 3 only

• Mutation 1 only

• Mutation 2 only

• Muations 1, 2, 3

Multiple Choice

Mutated DNA sequences that can be passed from parent to offspring --

• occur in somatic cells (body cells)
• occur in gametic cells (sex cells)
• are rejected by meiosis
• only occur if the parent is exposed to harmful substances

Multiple Choice

Would a mutation in the DNA of a skin cell be passed on to an organism's offspring?

• Yes, because any change to the DNA is passed on to the offspring

• Maybe. Sex cells only use half of the body's genetic code. It might get the copy of a gene that wasn't mutated.

• No. Only mutations that occur in the gametes (sex cells) are passed on to the offspring

• Without knowing the animal, it would be hard to tell whether or not the mutation would be passed on.

Multiple Choice

A single change in DNA base pair that changes one amino acid it codes for

• silent

• missense

• nonsense

Multiple Choice

A single change in DNA base pair that results in a STOP codon

• silent

• missense

• nonsense

Multiple Choice

A single change in DNA base pair that does not change the amino acid it codes for

• silent

• missense

• nonsense

Multiple Choice

Mutations in an organism's DNA may be either beneficial or harmful. Which statement best describes the concept of DNA mutation?

• DNA mutation is an alteration in DNA replication that always results in phenotypic change

• DNA mutation is a change in the way that genes reproduce themselves, which may or may not affect phenotypic characteristics

• DNA mutation is a change in the gene sequence, which sometimes results in phenotypic change. Mutations can be due to environmental factors, heredity, or a mistake in DNA replication

• DNA mutation is an alteration in the nucleus of a cell that makes certain genes unable to be copied

Multiple Choice

DNA mutations can be present in a gene for many reasons. Which of the following does NOT describe a reason genetic mutation may exist in a gene?

• When a cell dies, the DNA in the cell's nucleus can mutate

• Exposure to chemicals or radiation can cause mutation in DNA

• Mutations in DNA can be passed down from a parent to a child

• Polymerase can make a mistake in matching nucleotides during replication

Multiple Choice

Which mutation is most likely to create a phenotype change: CCC to CCG, UAU to UAA, GGU to GGG, or ACU to ACA?

• CCC to CCG
• GGU to GGG
• ACU to ACA
• UAU to UAA

Multiple Choice

A mutation deletes one base early in the gene. What is the effect on the protein?

• The protein is shorter but still functional.
• The protein is likely nonfunctional due to a frameshift mutation.
• The protein is unchanged and functions normally.
• The protein has enhanced activity due to the mutation.

Mendelian Genetics (Monohybrid Crosses)

• Allele: Different versions of a gene (T or t)

• Dominant: Allele that masks the recessive (capital letter: T)

• Recessive: Allele that is masked (lowercase letter: t)

• Genotype: Genetic makeup (TT, Tt, tt)

• Phenotype: Physical appearance (tall or short)

• Homozygous: Two identical alleles (TT or tt)

• Heterozygous: Two different alleles (Tt)

Multiple Choice

T - tall and t = short
In the punnett square below, what belongs in the missing square

• tt
• Tt
• Bb
• TT

Multiple Choice

What are the expected phenotypes of the offspring if two hybrid tall (Tt) pea plants are crossed?

• 1/4 will be short, 3/4 will be tall

• 
  2/4 will be short, 2/4 will be tall

• 3/4 will be short, 1/4 will be tall

• 4/4 will be short, 0/4 will be tall

Multiple Choice

What you see, or the physical appearance.

• Genotype
• Phenotype
• Homozygous
• Heterozygous

Multiple Choice

What is the probability of heterozygous offspring?

• 25%
• 50%
• 0%
• 100%

Multiple Choice

Which choice best represents the genotype of this cross?

• 1 Yy: 2 yy: 0 YY
• 2 Yy: 2 yy: 0 YY
• 3 Yy: 1 yy: 0 YY
• 1 Yy: 3 yy: 0 YY

Multiple Choice

Which of the following genotypes is homozygous dominant?

• A
• Aa
• AA
• aa

Multiple Choice

Which of the following genotypes is heterozygous?

• Bb
• BB
• bb
• B

Multiple Choice

Which of the following is homozygous recessive?

• Tt
• tt
• TT
• T

Multiple Choice

B = brown fur b = white fur

In the Punnett square, what is the probability for white fur?

• 0%

• 25%

• 50%

• 75%

Multiple Choice

The allele that is expressed over another.

• Dominant
• Recessive
• Genotype
• Phenotype

Multiple Choice

What is the genotypic ratio here?

• 25% blue eye 75 % brown eye 
• BB = 25% Bb = 50% bb = 25%
• BB= 50 % bb = 50%
• All brown eye

Multiple Choice

The mother's genotype is provided. Based on the probable offspring, what is the father's genotype?

• Heterozygous

• Homozygous dominant

• Homozygous recessive

• Tall

Mendel's Law of Segregation

• Each parent has 2 alleles for each trait

• During gamete formation (meiosis), alleles separate

• Each gamete gets only 1 allele

• Offspring get 1 allele from each parent

Multiple Choice

If a dominant allele is present, the trait will always appear in the organism.

• Law of Segregation

• Law of Dominance

• Law of Independent Assortment

Multiple Choice

Mendel's law of segregation states that during meiosis, the alleles that control each trait separate, and only _________________ from each pair is/are passed to the offspring

• one allele
• the dominant trait
• two alleles
• the recessive trait