BI111 Lecture Notes - Lecture 9: Mitosis, Meiosis, Down Syndrome

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26 May 2018

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Biology Review

Lesson 1.4

Abnormal Meiosis:

Non disjunction- not coming apart (failure of chromosomes to properly separate)

Mitosis- Failure of the sister chromatids to separate

Meiosis- Failure of homologous chromosomes to separate (severe damage)

Result of imbalanced chromosomes:

• One or more gametes lacks a chromosome (23-1)

• One or more gametes have an extra chromosome (23+1)

During Fertilization…

Normal gamete + Abnormal gamete

23+22=45 → Monosomy

23+24=47 → Trisomy

23+23=46 → normal

1. Non disjunction in autosomal chromosomes

• Trisomy 21 (down syndrome)

o Three #21 chromosomes

o The risk increases with the age of mother

• Trisomy 18 (Edwards syndrome)

o Heart abnormalities

o Kidney problems

o Low rate of survival

• Trisomy 13 Patau’s syndrome

o Mental and physical abnormalities

2. Non disjunction in sex chromosomes

• Turner syndrome (x)

o Female has single x chromosome

o Has male characteristics

• Klinefelters syndrome (xxy)

o Male has extra x chromosome

o High levels of female hormones at puberty

o Male is sterile (cant have kids)

• Triple x syndrome

o Occurs in female

o No unusual problems

Lesson 1.6

Heredity

Heredity- the passing of characteristics (traits) from parents to offspring

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Document Summary

Non disjunction- not coming apart (failure of chromosomes to properly separate) Mitosis- failure of the sister chromatids to separate. Meiosis- failure of homologous chromosomes to separate (severe damage) Result of imbalanced chromosomes: one or more gametes lacks a chromosome (23-1, one or more gametes have an extra chromosome (23+1) Heredity- the passing of characteristics (traits) from parents to offspring. Dominant- alleles of this type determine the expression of the genetic trait in offspring (uppercase letters) Recessive- alleles of this type are over ruled by dominant alleles (lowercase) Mendels law of heredity: law of segregation: two alleles for a trait separate when gametes formed, law of independent assortment: genes for different traits are inherited independently. A parent randomly passes one allele for each trait to each offspring: law of dominance: trait observed is the dominant trait. Incomplete dominance- no dominant or recessive gene, or the trait is controlled by many alleles.

Related Questions

-Complete the following sentences: metaphase of mitosis, prophase II of meiosis, crossing over, anaphase I of meiosis, variable, random fertilization, identical, random orientation, metaphase I of meiosis, prophase I of meiosis, metaphase II of meiosis, reduction division

Two processes that occur during meiosis produce genetically ____________ cells.

In a process called ____________ , paired homologous chromosomes align randomly at the cell equator. This occurs during this stage of cell division: ____________ .

In a process called ____________ , genetic material is exchanged between homologous chromosomes. This occurs during this stage of cell division: ____________ .

-Complete the following paragraph to describe nondisjunction and the resulting effects on chromosome number.

words: euploidy, primary nondisjunction, nomal, nondisjunction, secondary nondisjunction, homologous chromosomes, abnormal, trisomy, monosomy, sister chromatids, aneuploid

1.During meiosis I, ____________ separate and move towards opposite ends of the poles.

2.During meiosis II, ____________ separate and move towards opposite ends of the poles.

3.During meiosis I, if both members of a homologous pair go into the same daughter cell, ____________ is said to occur and no normal gametes are produced.

4.During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, ____________ is said to occur. Half the gametes are aneuploid while the other half are euploid.

5.If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

6.If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

Question 1

The process by which RNA is synthesized using DNA as a template is â¦

Select one:

a. replication

b. transcription

c. translation

d. inspiration

Question 2

Which of the following occurs during meiosis but not mitosis?

Select one:

a. DNA condenses into chromosomes

b. nuclear envelop disappears

c. homologous chromosomes separate

d. sister chromatids separate

Question 3

Which part of the animal life cycle is haploid?

Select one:

a. gamete

b. zygote

c. sporophyte

d. spore

Question 4

Single celled eukaryotic organisms are â¦

Select one:

a. viruses

b. bacterial

c. archaea

d. protists

Question 5

Which type of cellular division results in the formation of diploid cells from a diploid parent cell?

Select one:

a. mitosis

b. meiosis

c. interphase

d. A and B but not C

e. all of the above

Question 6

A sequence of DNA that codes for a single protein is a â¦

Select one:

a. gene

b. ribosome

c. mRNA

d. none of the above

Question 7

Which of the following is characteristic of animals?

Select one:

a. heterotrophic

b. sexual reproduction

c. embryonic development

d. all of the above

Question 8

All genes have only two possible alleles.

Select one:

True

False

Question 9

The presence of membrane-bound organelles is characteristic of â¦

Select one:

a. prokaryotes

b. viruses

c. bacteria

d. eukaryotes

Question 10

What are the building blocks of proteins?

Select one:

a. fatty acids

b. amino acids

c. nucleic acids

d. all of the above

Question 11

During which phase of the cell cycle does DNA replication occur?

Select one:

a. Mitosis

b. Interphase

c. Meiosis

d. Replicosis

Question 12

Which of the following characteristic is shared among fungi and animals?

Select one:

a. autotrophic

b. heterotrophic

c. cell walls

d. absorb nutrients

Question 13

A error in DNA replication that goes unrepaired is a â¦

Select one:

a. chromosome

b. chromatid

c. mutation

d. none of the above

Question 14

Alternate forms of a gene are called ________.

Select one:

a. chromatids

b. chromosomes

c. ribosomal subunits

d. alleles

Question 15

The physical expression of a genotype is the phenotype.

Select one:

True

False

Question 16

In complete dominance, a heterozygous genotype results in â¦

Select one:

a. a recessive phenotype

b. a dominant phenotype

c. a third and unique phenotype

d. none of the above

Question 17

Which theory explains the evolution of eukaryotes from prokaryotes?

Select one:

a. phagocytosis

b. endosymbiosis

c. pinocytosis

d. none of the above

Question 18

Which scientist experimented with plants to describe patterns of inheritance?

Select one:

a. Mendel

b. Chase

c. Einstein

d. Watson

Question 19

Which cellular organelle contains aerobic cellular respiration?

Select one:

a. chloroplasts

b. mitochondria

c. nucleus

d. lysosome

Question 20

Which of the following statements is false?

Select one:

a. Haploid gametes are formed by meiosis

b. Mitosis forms genetically identical daughter cells

c. Mitosis results in the formation of four daughter cells from a single parent cell

d. Mitosis forms diploid daughter cells from a diploid parent cell

Question 21

The first forms of life on Earth were ________.

Select one:

a. plants

b. microorganisms

c. birds

d. dinosaurs

Question 22

Which of the following is used to separate chromosomes during nuclear division?

Select one:

a. cytoskeleton

b. microtubules

c. actin and myosin

d. amoeboid movement

e. all of the above

Question 23

Which generation is most dominant in more primitive plants?

Select one:

a. bryophyte

b. sporophyte

c. gametophyte

d. androphyte

Question 24

Which of the following is characteristic of plants?

Select one:

a. autotrophic

b. contain chloroplasts

c. multicellular

d. all of the above

Question 25

During which phase of mitosis do chromosome line up along the middle of the cell?

Select one:

a. prophase

b. metaphase

c. anaphase

d. telophase

Question 26

During which phase of mitosis does DNA condense into distinct chromosomes?

Select one:

a. prophase

b. metaphase

c. anaphase

d. telophase

Question 27

The process by which DNA is used as a template to make new DNA is â¦

Select one:

a. translation

b. replication

c. transcription

d. allocation

Question 28

Which of the following is characteristic of plant but not animal cells?

Select one:

a. chloroplasts

b. water vacuole

c. cell wall

d. all of the above

Question 29

Which meiotic division is most like mitosis?

Select one:

a. Meiosis I

b. Meiosis II

c. Meiosis III

d. Meiosis IV

Question 30

Which enzyme catalyzes replication?

Select one:

a. DNA polymerase

b. RNA polymerase

c. Ribosome

d. all of the above

BI111 Lecture Notes - Lecture 9: Mitosis, Meiosis, Down Syndrome

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