EDUC109 Study Guide - Final Guide: Thymine, Adenine, Guanine

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31 May 2018

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Genetics

Genetics=Study of the information controlling the development and functioning of living things

Gregor Mendel (1822-84)

-Performed controlled experiments, made careful observations of the inheritance of characteristics (traits) of

pea plants (began in 1856).

-Recognised a pattern in the inheritance of pea plant characteristics but was unable to explain why.

-Used his knowledge of mathematics to predict outcomes of breeding pea plants from any two parents.

-He devised principles of inheritance which are now called Mendel’s Laws.

-Tallness is determined by a factor, that he called T, and dwarf by a factor he called t.

-Tallness trait is dominant and the dwarf trait is recessive (when two factors are together then the tallness trait

masks/hides the dwarf trait and only tall plants are produced).

-Peas have two factors for each characteristic; they can be the same (TT or tt) or different (Tt).

-Pea plants only pass on one of their two factors to their pollen and egg cells.

-Each sperm cell and egg cell (gamete) receives one or the other factor in equal probability.

Law of Segregation

-Individuals carry pairs of factors (alleles) for a trait. During the formation of gametes (eggs or sperm), the two

alleles responsible for a trait separate from each other.

-Alleles for a trait are then recombined at fertilization, producing the genotype for the traits of the offspring.

-Tall (T) and dwarf (t) are different forms (alleles) of the gene which control the height of pea plants.

-Genotype=Genetic make-up e.g. TT, Tt and tt

-Phenotype=physical appearance e.g. Tall (TT or Tt), dwarf (tt)

-Homozygous= (pure-breeding) plants have the same alleles e.g. TT or tt.

-Heterozygous= Plants have the two different alleles e.g. Tt.

-Dominant trait=Ability to roll your tongue, dimples, free ear lobes

-Autosomes=Chromosomes that exist in pairs. Located on one of our 23 pairs of autosomes

-Gregor Mendel is the father of genetics because he discovered dominant and recessive traits and also that

traits are randomly and statistically given from parents to a child. His discoveries established the fundamentals

of genetics that are understood in modern science.

X & Y Chromosomes

-The sex of an individual is determined by a pair of sex chromosomes (gonosomes).

-Females typically have 2 of the same kind of sex chromosome (XX), and are called the homogametic sex.

-Males typically have 2 distinct sex chromosomes (XY), and are called the heterogametic sex.

-Autosomal DNA=An autosome is any of the numbered chromosomes, as opposed to the sex chromosomes.

Humans have 22 pairs of autosomes and one pair of sex chromosomes (the X chromosome and the Y

chromosome).

Punnet Square

-Used to predict an outcome of a particular cross or breeding experiment.

-Examples of traits are the presence of freckles, hair colour, and skin tone.

-Freckles or ephelis are yellowish or brownish macules that develop

on the exposed parts of the skin, especially in people with light complexion.

-The parents heterozygous genetypes are: Mum= Ff Dad= Ff

-Therefore, there’s a 75% probability that their child will have freckles, or a

25% of a child with no freckles.

-When a dominant and recessive gene are both present in a single offspring,

that the dominant trait will show in the offspring, but this may not be thcase

for their offspring.

F f

FF Ff

Ff ff

F= Freckles (Dominant)

f= No freckles (Recessive)

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Document Summary

Genetics= study of the information controlling the development and functioning of living things. Performed controlled experiments, made careful observations of the inheritance of characteristics (traits) of pea plants (began in 1856). Recognised a pattern in the inheritance of pea plant characteristics but was unable to explain why. Used his knowledge of mathematics to predict outcomes of breeding pea plants from any two parents. He de(cid:448)ised prin(cid:272)iples of inheritan(cid:272)e (cid:449)hi(cid:272)h are no(cid:449) (cid:272)alled mendel"s la(cid:449)s. Tallness is determined by a factor, that he called t, and dwarf by a factor he called t. Tallness trait is dominant and the dwarf trait is recessive (when two factors are together then the tallness trait masks/hides the dwarf trait and only tall plants are produced). Peas have two factors for each characteristic; they can be the same (tt or tt) or different (tt). Pea plants only pass on one of their two factors to their pollen and egg cells.

Related Questions

If an organismâs diploid chromosome number is 18, how many different possible combinations of homologous chromosomes lining up during meiosis exist for the eggs or sperm produced by that organism?

	A.	512
	B.	9
	C.	18
	D.	128
	E.	36

At the end of metaphase I, _______________ separate.

	A.	sister chromatids
	B.	germ cells
	C.	homologous chromosomes
	D.	haploid chromatids
	E.	centrioles

Mendel observed that dominant traits

	A.	are seen in all of the F1 hybrid pea plants in his experiments.
	B.	are expressed in all plants.
	C.	were absent in the F1 generation of pea plants that he used in his experiments.
	D.	were the only traits seen in the F2 generation of pea plants in his experiments.
	E.	are only expressed in hybrids.

Cytokinesis in plant cells differs from cytokinesis in animal cells because

	A.	there is no difference.
	B.	in plant cells, the cell plate must also divide into two parts.
	C.	the contractile protein, actin, is important only in plant cells.
	D.	plant cells have a rigid cell wall.
	E.	a contractile ring forms only in plant cells.

Sickle cell anemia is an example of what type of inheritance?

	A.	complete dominance
	B.	incomplete dominance
	C.	codominance
	D.	multiple alleles
	E.	recessive dominance

Which of the following statements is true:

	A.	The dominant allele is masked in homozygous dominant individuals.
	B.	With recessive genetic disorders, if both parents are carriers, the offspring will all be affected.
	C.	In carriers, the recessive allele causes an intermediate phenotype.
	D.	In recessive genetic disorders, the mother and/or father of an affected individual must also be affected.
	E.	With dominant genetic disorders, the mother and/or father of an affected individual must also be affected.

Skin cancers typically develop in the

	A.	upper layers of the epidermis.
	B.	lower layers of the dermis.
	C.	subcutaneous layer.
	D.	lower layers of the epidermis.
	E.	upper layers of the dermis.

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

	A.	1/2
	B.	0
	C.	1/16
	D.	1/4
	E.	1/8

The genetic makeup of a particular trait in an individual is its

	A.	genotype.
	B.	heterozygosity.
	C.	phenotype.
	D.	filial.
	E.	dominance.

What structure holds the sister chromatids to the spindle fibers?

	A.	chromatin
	B.	kinetochore
	C.	MPF
	D.	centromere
	E.	cyclin

If you view a cell in which the genetic material is beginning to be visible as separate bodies, and the nucleus has disappeared from view, you may surmise that the cells is in

	A.	telophase.
	B.	anaphase.
	C.	interphase.
	D.	metaphase.
	E.	prophase.

Gregor Mendel was successful in his analysis of the genetics of pea plants because

	A.	he examined and analyzed both the F1 and F2 generations.
	B.	he studied the parental plants to determine their differences.
	C.	he decided to only look at his results in an objective manner.
	D.	he studied a trait that had a strange inheritance pattern.
	E.	pea plants have genetics different from other organisms.

Tall corn plants (T) are dominant to dwarf plants (tt). Solid green leaves (G) are dominant to leaves with a white tip (gg). A cross between two corn plants yielded the following phenotypes: 51 tall plants with a white tip on their leaves; 43 dwarf plants with solid leaves; 48 dwarf plants with white tips on their leaves; 45 tall plants with solid leaves. What are the genotypes of the parents that produced these plants?

	A.	None of the above
	B.	TtGg x Ttgg
	C.	ttGG x TTgg
	D.	TtGg x TtGg
	E.	TtGg x ttgg

In humans, a gene that has been identified as causing a type of skin cancer is the

	A.	superwoman echidna.
	B.	mutant superman.
	C.	sonic hedgehog.
	D.	mutant mole rat.
	E.	superhero aardvark.

The segregation principle states that in sexually reproducing diploid organisms the two copies of each gene

	A.	segregate from each other during meiosis.
	B.	must always be the same allele.
	C.	separate from each other during mitosis.
	D.	will both wind up in either the sperm or egg.
	E.	move together as a unit during meiosis.

In what phases is the genetic material in the cell correctly referred to as chromatids?

	A.	metaphase and telophase
	B.	anaphase and metaphase
	C.	interphase and telophase
	D.	interphase and prophase
	E.	metaphase and prophase

Consider two traits for an organism, determined by two genes, each of which is governed by at least two alleles. In the case of a dihybrid individual, the gametes formed will be of either the parental type or the recombinant type. Recombinant type gametes are formed because of

	A.	the principle of dihybrids.
	B.	multiple alleles.
	C.	heterozygosity.
	D.	incomplete dominance.
	E.	independent assortment.

An allele is

	A.	an alternate form of a gene.
	B.	always recessive.
	C.	the main factor determining a trait.
	D.	always one of a pair.
	E.	the dominant form of a gene.

After the DNA is replicated, and it condenses in prophase, two identical rods of DNA are seen. These are

	A.	spindle fibers.
	B.	kinetochores.
	C.	chromatids.
	D.	chromatin.
	E.	centromeres.

Special cells found in the gonads that give rise to gametes upon division are called

	A.	egg cells.
	B.	somatic cells.
	C.	germ cells.
	D.	stem cells.
	E.	basal cells.