Unit 3: Genetics Review

​DNA vs RNA

DNA contains the information to code ​for proteins.

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​DNA is found in the nucleus and cannot leave. However, proteins are made at the ribosome. DNA's code mut be copied so that the information can leave the nucleus. RNA is the complementary copy of DNA's code.

Multiple Choice

In RNA, Adenine (A) pairs with...

• T

• U

• C

• G

Multiple Choice

Which of the following is a characteristic of RNA?

• Double stranded

• Contains the base Thymine

• Can leave the nucleus

• Contains the sugar deoxyribose

Types of RNA

3 Types:​

• Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes

• Ribosomal RNA (rRNA), along with protein, makes up the ribosomes

• Transfer RNA (tRNA) transfers amino acids to the ribosomes

  where proteins are synthesized​

Types of RNA​

​

Multiple Choice

Which type of RNA is responsible for bringing amino acids to the ribosome?

• mRNA

• rRNA

• tRNA

• DNA

Multiple Choice

What would be the complementary RNA sequence for the following DNA sequence?

ATTCGT

• UAAGCA

• TAAGCA

• GCCTAC

• UGCUAC

Pathway to Making a Protein​

​DNA -> RNA -> Protein

Subject | Subject

Some text here about the topic of discussion

Step 1: Transcription

DNA -> RNA

• The process of copyingthe sequence of one strand of DNA, the

  template strand

• mRNA copies the template strand​​

• This process occurs in the nucleus ​

• mRNA is complementary to DNA (not an exact copy)​

Step 2: Translation

RNA -> Protein

• Translation is the process of decoding the mRNA into a protein

• Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins​

• tRNA brings the correct amino acid as coded for in the mRNA​

• ​Occurs in the cytoplasm at the ribosome

Multiple Choice

What is the name of the process in which DNA is transcribed into RNA?

• Photosynthesis

• Protein Synthesis

• Translation

• Transcription

Multiple Choice

What amino acid is coded for by the RNA sequence below?

AGG

• Gly

• Leu

• Arg

• Val

Multiple Choice

Which process is shown?

• Replication

• Transcription

• Translation

• Photosynthesis

The number of nucleotides changes.

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Insertion: Adding a nucleotide

Deletion: Removing a nucleotide​

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​

​Frameshift

The number of nucleotides stays the same, but a nucleotide changes.

Substituion

Mutations - Changes in nucleotides sequences

Some text here about the topic of discussion

Multiple Choice

What type of mutation has occured to the DNA sequence below?

Original DNA: AAC - GTA

Mutated DNA: AAG - TA

• Substitution

• Deletion

• Insertion

• Non - sense

Multiple Choice

Select the DNA sequence below that demonstrates a subsitution mutation.

Original DNA: AAT - GCC

• Mutated DNA:

  AAT - GGC - C

• Mutated DNA:

  AAG- CC

• Mutated DNA:

  ATT - GCC

• AAT - TGC - C

Open Ended

Meiosis happens in what kind of cells?

Multiple Choice

Where do we normally find DNA within a cell?

• In the cytoplasm

• In the nucleus

• In the vacuole

• In the smooth ER

Multiple Choice

When does crossing over occur?

• Telophase II

• Metaphase I

• Metaphase II

• Prophase I

Multiple Choice

When does the independent assortment of chromosomes occur?

• Telophase II

• Metaphase I

• Metaphase II

• Prophase I

Multiple Choice

Does the cell undergo interphase a second time following telophase I?

• Yes

• No

Open Ended

At the end of meiosis, the haploid cells produced are called what?

Multiple Choice

At the end of meiosis, how many daughter cells are produced?

• 1

• 2

• 3

• 4

Multiple Choice

A cell containing 40 chromosomes at the beginning of mitosis would, at its completion, produce cells containing how many chromosomes?

• 10

• 20

• 40

• 80

Multiple Select

What are three things that happen during Meiosis that DOES NOT occur in Mitosis?

• Chromosomes duplicate

• Independent Assortment

• Mutiple cells are produced

• Genetic Variation

• Crossing Over

Multiple Choice

A cell containing 20 chromosomes (diploid) at the beginning of meiosis would, at its completion, produce cells containing how many chromosomes?

• 10

• 5

• 40

• 20

Mendel and Modern Genetics

Mendel lived in the 1800s and knew nothing of genetics, yet his findings have been accepted by modern geneticists

Mendel and His Thousands of Pea Plants

• Mendel performed thousands of experiments with the pea plants over many years

• He noticed that certain traits would appear in one generation and then disappear in the next generation

• Then, in later generations of pea plants, the trait that had disappeared would show up again.

An Example of Disappearing and Reappearing Traits

• Purple versus white flowers

• Generation 1: True-breeding purple crossed with true-breeding purple produced all purple flowers (offspring 1)

• Generation 2: Offspring 1 (all purple flowers) crossed with true-breeding white flowers produced all purple flowers (Offspring 2)

• Generation 3: Offspring 2 self-pollinates (basically reproduces with only itself) and produces mostly purple and some white flowers.

Why did the white flower trait not show up in one generation and then showed up in the next generation?

• Mendel observed this happening over and over and came to the conclusion that the purple was sometimes able to "block" the appearance of the white flowers.

• The purple trait was "dominant" over the white trait.

• The white flower trait was "recessive".

Law of Dominance

• a natural law stating that a dominant allele will always mask a recessive allele

Dominant versus Recessive

• Dominant- a trait that is expressed over another trait

• Recessive- a trait that can be hidden by another trait

• If one trait is dominant and another trait is recessive, and either one appears at different times throughout generations, Mendel concluded that there must be two factors involved in heredity- one factor from each parent.

• Modern genetics calls these factors "alleles".

Multiple Choice

What observation did Mendel make about certain traits that led him to conclude that some traits were dominant to other traits?

• Some traits appeared once every 10 generations.

• Some traits appeared twice every 10 generations.

• Some traits never appeared.

• Some traits appeared in most or all of the generations.

Multiple Choice

Mendel also observed seed color in pea plants. In a study of several generations, yellow seeds appeared more frequently than green seeds. Which of the following is most likely the reason for this observation?

• Green seeds are dominant to yellow seeds.

• Yellow seeds are recessive to green seeds

• Green seeds are recessive to yellow seeds.

Mendelian Genetics in Animals

• There are some traits in animals that follow the pattern of Mendelian genetics.

• Fur color, eye color, length of ears, etc. are all traits that can follow the law of dominance

Modern Mendelian Genetics

• We now know that each trait in an organism is controlled by genes (segments of DNA that code for specific proteins that control specific traits).

• However, a single gene has many different variations within it that provides for diverse options

• Alleles- different variations of the same gene

• There are two alleles for each trait- one from each parent

Possible Alleles

• homozygous (or pure)- having two of the same alleles for a trait 

• heterozygous (or hybrid)- having two different alleles for a trait

• Homozygous dominant- having two dominant alleles for a trait

• Homozygous recessive- having two recessive alleles for a trait

Representing Alleles

• Alphabetic letters represent alleles

• lowercase letters represent "recessive" alleles

• uppercase, or capital, letters represent "dominant" alleles

• 
  

Representing Alleles, continued

• **Recall that there are two alleles for each trait

• two capital letters (ex: TT) are called homozygous dominant alleles

• two lowercase letters (ex: tt) are called homozygous recessive alleles

• an allele pair with one capital letter and one lowercase letter (ex: Tt) are called heterozygous

Multiple Choice

Which of the following is correct?

• Yy is homozygous dominant.

• YY is heterozygous.

• yy is homozygous recessive.

• YY is homozygous recessive.

Multiple Choice

Which of the following represents a heterozygous genotype?

• Aa

• AA

• aa

• Ab

Multiple Choice

A recessive trait would appear in the phenotype of which of these?

• BB

• bb

• Bb

• Bf

Multiple Choice

Which of the following best describes Mendel's law of dominance?

• When an organism has two different alleles of the same gene, both genes will be expressed equally.

• When an organism has two alleles, one of genes will be expressed and the other will be hidden.

• When an organism has two different alleles of the same gene, one will always be dominant.

• The stronger of the two genes will be expressed.

Multiple Choice

Which of the following is NOT a trait that Mendel observed in his pea plants?

• seed color

• seed shape

• length of leaves

• flower color

Multiple Choice

You have two flowers. The purple allele (P) is dominant over the white allele (p).

You breed a homozygous dominant flower (PP) with a homozygous recessive flower (pp).

What color will the offspring be?

• All purple

• All white

• All pink

• Half purple, half white.

Mendelian Genetics

Remember:​

Homo = same (TT ...tt ... RR ... aa)

Since homozygous is same, we have to clarify,

is it dominant (AA) or recessive (aa)

AA= homozygous dominant

aa= homozygous recessive

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Mendelian Genetics

Hetero = different (Tt ... Rr ... Aa)

Heterozygous means you inherited one of each allele.

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But heterozygous gives the same phenotype as homozygous dominant.

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​The only way to show

the recessive trait is to

have TWO recessive

alleles (bb)

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Non-Mendelian Genetics

Some traits don’t follow the simple dominant/recessive rules that Mendel first applied to genetics.

Traits can be controlled by more than one gene.

Some alleles are codominant.

Some alleles are neither dominant nor recessive.

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Multiple Choice

Red hair (R) and white hair (W) are codominant in cows.

Cross a white cow (WW) with a red cow (RR).

What color will the calves be?

• White

• Red

• Pink

• Roan

  (Mix of white spots and red spots)

Non-Mendelian Genetics

Codominance

​

Two alleles are equally dominant and are both expressed in the phenotype.​

Ex: Coat color in cows

​

RR: Red

WW: White

RW: Roan, white with red spots (NOT pink!)

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Multiple Choice

You have two flowers. The red allele shows incomplete dominance over the white allele.

You breed a red flower (RR) with a white flower (rr).

What do you think the offspring will look like?

• All red

• All white

• All pink

• Half red, half white.

Non-Mendelian Genetics

Incomplete Dominance​

​

One allele is not completely

dominant over another.

The heterozygous phenotype is a

blending of the two homozygous phenotypes.

Example: four o’clock flowers

rr = red

ww = white

rw = pink (blending of the two alleles)

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Incomplete dominance vs. Codominance

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Incomplete dominance mixes like paint.

Red + White = pink (in between phenotype)

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Codominance mixes like marbles.​

Red + white = distinct patches of red and white (both phenotypes)

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​

Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have red flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have pink flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red flowers (R) show incomplete dominance over white flowers (r). Cross two pink flowers (Rr).

What percentage of the offspring will have white flowers?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be red?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be white?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Red hair (R) and white hair (W) are codominant in cows. They produce a cow with both red and white spots, called "roan", when mixed.

Cross a white cow (WW) with a roan cow (RW).

What percentage will be roan?

• 0%

• 25%

• 50%

• 75%

• 100%

Multiple alleles and Codominance -

BLOOD TYPES

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Human blood has three alleles.

A and B are both codominant.

(I^A and I^B)

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o is recessive (i)

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Individuals can be type A, type B, type AB, or type O (recessive).

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Blood Groups

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​Type A:​

Homozygous: (AA) or (I^AI^A)

'

'

​Heterozygous: (Ao) or (I^Ai)

'

'

Can give blood to: A & AB

'

'

Can get blood from: A & O

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Blood Groups

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​​Type B:​

Homozygous: (BB) or (I^BI^B)

'

'

​Heterozygous: (Bo) or (I^Bi)

'

'

Can give blood to: B & AB

'

'

Can get blood from: B & O

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Blood Groups

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​​Type O:​

Homozygous recessive: (oo) or (ii)

'

'

​Can give blood to: A, B, AB, O

Universal donor

'

'

Can get blood from: O

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Blood Groups

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​​Type AB:​

Heterozygous codominant:

(AB) or (I^AI^B)

'

'

​Can give blood to: AB

'

'

Can get blood from: A, B, AB, O

Universal receiver

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BLOOD TYPES

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People with blood group O are called "universal donors."

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People with blood group AB are called "universal receivers."

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If you have O blood hospitals will beg you to donate!

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BLOOD TYPE Reference

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​Type A:​

(I^AI^A) or (I^Ai) ; (AA) or (Ao)​

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Type B:

(I^BI^B) or (I^Bi) ; (BB) or (Bo)​

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Type AB:

(I^AI^B) ; (AB​)

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Type O:

(ii) ; (oo)

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​These two Punnett Squares are the same. They just use different ways of representing the A, B, and o alleles.

A mother with type O blood gives birth to a baby.

The father has type AB blood.

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What are some possible blood types that the baby could have?​

​

____ x ____

father x mother

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Phenotypes:​

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​Type A:

Type B:​

​Type AB:

Type O:​

In 1968, a couple accused a hospital of switching their baby with another. DNA technology was unavailable so they used blood type to test if the baby was theirs or not.

Mom is type A and dad is type AB. The baby is type O blood.

Did the hospital make a mistake?

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​Phenotypes:​

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​

​

​

​

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​Type A:

Type B:​

​Type AB:

Type O:​

BLOOD TYPE Reference

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​Type A:​

(I^AI^A) or (I^Ai) ; (AA) or (Ao)​

​

Type B:

(I^BI^B) or (I^Bi) ; (BB) or (Bo)​

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Type AB:

(I^AI^B) ; (AB​)

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Type O:

(ii) ; (oo)

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​

​

​

​

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​These two Punnett Squares are the same. They just use different ways of representing the A, B, and o alleles.

In 1968, a couple accused a hospital of switching their baby with another. DNA technology was unavailable so they used blood type to test if the baby was theirs or not.

Mom is type A and dad is type AB. The baby is type O blood.

Did the hospital make a mistake?

​

​____ x _________

father x mother

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Phenotypes:​

​

​

​

​

​

​

​

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​Type A:

Type B:​

​Type AB:

Type O:​

A woman with type A blood has a child with type B blood. How is this possible?

​

Start with what you know and fill that in!

​

____ x ____

father x mother

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Phenotypes:​

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​

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​

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​Type A:

Type B:​

​Type AB:

Type O:​