Bio exam 4 Human Genome

How many total chromosomes in humans? 

46

How many total autosomes are in humans?

22 pairs/ 44

How many sex chromosomes are in humans?

2

Differences between males and females?

Males - XY

Females - XX

What is a karyotype?

An individual’s chromosome composition

Describe the process of karyotyping

1. Add tissue sampling

2. Stimulate mitosis

3. Incubate 

4. Add chemical to stop mitosis in metaphase

5. Transfer cells

6. Add fixitive

7. Move cells to slide

8. Observe and photograph the chromosomes

9. Cut out & arrange chromosomes into a karyotype

What is a pedigree? 

A diagram that shows the genetic relationships between individuals in a family across generations

How are females represented? 

Circle shape

How are males represented?

Square shape

What does wild type mean?

The phenotype that is most commonly observed in natural populations

Give two examples of recessive genetic diseases

• Albinism

• sickle- cell anemia

Give two examples of dominant genetic diseases

• Alzheimer’s disease

• Achondroplasia

How many defective genes do you have to inherit to get a recessive genetic disease?

two defective copies

How many defective genes do you have to inherit to get a dominant genetic disease?

one defective copy of the gene

   When could being heterozygous for sickle cell anemia be an advantage?

Being heterozygous for sickle cell anemia can provide a protective advantage against malaria while maintaining a normal phenotype.

What is polyploidy?

Presence of multiple sets of chromosomes

 What normally causes polyploidy?

• Chromosomes fail to separate during meiosis

• Fertilization of an egg by more than one sperm

What happens in animals when polyploidy happens?

Cause of miscarriages

What happens in plants when polyploidy happens?

Enlarged endosperm

What is disomy?

• Normal chromosome number

• 2 of each chromosome

What is aneuploidy in general?

Abnormality caused by the presence of one extra chromosome or the absence of one chromosome

 What is Down syndrome?

• Trisomy 21

• Most common chromosome number abnormalities in humans

• Mental and physical retardation

  What increases the risk of having a Down syndrome baby?

 A mother over 35 having a baby

 Klinefelter Syndrome

(What chromosomes?Who? Appearance?)

• XXY

• Males with 47 chromosomes

• Small testes (produce few sperm/ sterile)

• Female breast like development

Turner Syndrome

(What chromosomes?Who? Appearance?)

• XO

• Only one sex chromosome. Females

• Female features are underdeveloped. Especially ovaries/ sterile

XYY Karyotype

(Characteristics)

• Males that are fertile

• Tall

• Acne 

• Normal IQ

• Violent behavior

 Triplo-X Karyotype

• Female with normal characteristics

• Two of the x’s become barr bodies

In general, is aneuploidy more severe when they involve autosomes or sex  chromosomes?  

Autosomes

What is a Barr body? 

inactivated X chromosome found in the nucleus of somatic cells in female mammals

What causes Cri du chat?  

Deletion of a segment in chromosome #5

What happens to the baby?

• Moon face

• Distinctive cry like a kitten

When can Amniocentesis be done?

16 weeks or later

What is the turnaround time of Amniocentesis?

1-2 weeks after the procedure

How invasive is Amniocentesis?

Amniocentesis is a minimally invasive procedure

What is used to diagnose Amniocentesis? 

• Amniotic fluid analysis

• genetic testing

When can Chorionic villi sampling be done?

8 weeks

What is the turnaround time of Chorionic villi sampling?

1-2 wks

How invasive is Chorionic villi sampling?

It is considered invasive because it involves removing tissue from the placenta

What is used to diagnose Chorionic villi sampling? 

• Ultrasound

• genetic testing

List two different vectors that have been used in successful gene therapy

• Stem cells

• viruses

Give a couple of examples of diseases that have been successfully treated with gene therapy

• Immune deficiency 

• Melanoma

• Hemophilia

  What are chimeras?

an organism composed of cells from two or more genetically distinct individuals

 For the human and pig chimeras, what kind of human cells are used?

Human induced pluripotent stem cells

What embryonic stage from the pig are they introduced into?  

The blastocyst stage.

What is the intended purpose of this research?

To create genetically modified organs for transplantation and study disease modeling