Week 19: Genotype to Phenotype I

Question 1

phenotype

Answer 1

An organism’s visible, expressed traits

An organism’s phenotype is all of its observable characteristics — which are influenced both by its genotype and by the environment.

Question 2

how does natural selection work in regards to phenotypes

Answer 2

Natural selection acts by selecting FOR the best phenotypes, and/or AGAINST those that do not succeed in a given environment

Therefore phenotypes must vary in order for natural selection to cause change over time

Question 3

Where does phenotypic diversity come from

Answer 3

Genetic diversity

Question 4

where does Genetic diversity come from

Answer 4

Genetic mutation

Horizontal Gene Transfer (Prokaryotes)

Sexual Recombination of Genes (Eukaryotes)

Question 5

define Mutation

Answer 5

the alteration of the nucleotide sequence of DNA or RNA

Question 6

what is the only source of novel traits

Answer 6

Mutation

Question 7

Mutations may be harmful, neutral, or beneficial… most mutations are ……

Answer 7

neutral or harmful

Question 8

Effects of a mutation depend on:

Answer 8

All the other genes in an organism

The organism’s environment

Question 9

A beneficial mutation in a gene may increase fitness Which will result in what?

Answer 9

more of the organism’s genes are passed on through
reproduction to the next generation

Question 10

Mutation is entirely random with regard to where in the genome it occurs. True or False

Answer 10

true

Question 11

Somatic (Body) mutations

Answer 11

occur in the cells of the body, and cannot be inherited

spread during mitosis, or regular cell division.

Question 12

Germline (gamete) mutations

Answer 12

occur in gametes (eggs or sperm) and can be potentially passed on to offspring to either harmful, neutral or beneficial effect

Germline mutations occur during meiosis, or cell division to produce the gametes.

Question 13

what are the different types of point mutations

Answer 13

transition/substitution

transversion/inversion

insertion

deletion

Question 14

what is “substitution” point mutation

pg.8

Answer 14

one nucleotide in a DNA sequence is replaced by another nucleotide

ex:
AT pair replaced by GC pair

Question 15

what is “inversion” point mutation

pg.8

Answer 15

the reversal of a segment of DNA within a chromosome

ex:
AT pair replaced by TA pair

Question 16

what is “insertion point mutation

pg.8

Answer 16

involves the addition of one or more nucleotides into the DNA sequence

ex:
GC pair inserted

Question 17

what is “deletion” point mutation

Answer 17

the removal or loss of one or more nucleotides from a DNA sequence

ex:
AT pair deleted

Question 18

question on page 10

Answer 18

insertion

Question 19

question on page 13

Question 20

question on page 15

Question 21

what point mutation is most likely to produce a nonfunctional protein/most harmful

Answer 21

Frameshift mutations = insertions/deletions

Since the genetic code is read in triplets (codons), a frameshift mutation alters the reading frame, leading to changes in all the amino acids that would occur after that

Question 22

Most mutations have little to no effect on organisms or their offspring, because…

Answer 22

Most mutations occur in somatic cells.

There is redundancy in translation to protein.

Diploid organisms have a second, functional copy of the gene in the corresponding chromosome

detailed explaination: The presence of a second, functional copy of a gene in diploid organisms provides a level of genetic redundancy that can mitigate the effects of certain mutations.

Question 23

How does sex produce variation

(look at page 19)

Answer 23

1. Alleles comes from two different parents

2.Reassortment of homologues

3.Crossing over

Question 24

genotype

Answer 24

set of genes that an organism carries

Question 25

An organism’s phenotype is all of its observable characteristics — which are influenced by both …

Answer 25

genotype and environment

Question 26

Differences in the genotypes can produce different phenotypes. True or False

Answer 26

true

Question 27

who is Gregor Mendel

Answer 27

often referred to as the “father of modern genetics” for his pioneering work on the inheritance of traits in pea plants

Question 28

what are the three main principles of Mendel’s Laws of Inheritance

Answer 28

Law of Segregation

Law of Independent Assortment

Law of Dominance

Question 29

what is the “Law of Segregation”

Answer 29

alleles of a given gene are separated into different gametes

This law explains why offspring inherit one allele from each parent, leading to the variation of traits in subsequent generations.

Question 30

What does the “R” gene do?

(Molecular Basis of Wrinkled vs. Round Peas)
(Mendel’s Laws of Inheritance)

Answer 30

The “R” gene DNA encodes a Starch Branching Enzyme protein (SBE1)

Question 31

How does the SBE1 protein lead to round seeds?

Answer 31

It gives rise to highly branched starch (amylopectin)

Highly branched starch in the seeds leads to seeds with low water content. When the seeds dry, they stay round.

Question 32

question on page 30

Question 33

What is a dominant allele/trait

Answer 33

the allele that determines the phenotype in a heterozygote

Question 34

How are Dominant alleles typically expressed

Answer 34

represented by uppercase letters (e.g., “A”)

Question 35

how are recessive alleles typically expressed

Answer 35

represented by lowercase letters (e.g., “a”)

Question 36

when is a recessive allele/trait expresed

Answer 36

only expressed in the phenotype when two copies of the allele (homozygous recessive) are present

If a dominant allele is present, it masks the expression of the recessive allele.

Question 37

what does Homozygous mean

Answer 37

an individual carries two copies of the same version of a gene: ex. RR

Question 38

what does Heterozygous mean

Answer 38

an individual carries two different versions of the same gene: ex. Rr.

Question 39

A heterozygote will always display the phenotype of which allele/trait: dominant or recessive

Answer 39

dominant allele

the R. RR and Rr will have the same gene expression, and the same phenotype.

Question 40

what are alleles

Answer 40

alternative versions or variants of a gene that are found at the same location (locus) on a chromosome.

Question 41

Each individual inherits two alleles for each gene, one from each parent. These alleles may be identical (homozygous) or different (heterozygous). True or false

Answer 41

true

Question 42

question on page 34

Answer 42

C