Genetics, Multiples and Unusual Births Study Guide

Question 1

What are Genetics?

Answer 1

Genetics is the study of the way animals and plants pass on information to their offspring

Question 2

What are examples of genetics?

Answer 2

Eye color, hair color, height, body build, blood types, intelligence, gender, etc.

Question 3

What are Chromosomes? Where can you find them?

Answer 3

Chromosomes are threadlike structures of nucleic acids and protein found in the nucleus of most living cells that carry genetic information in the form of genes

Question 4

How many chromosomes are you supposed to have?

Answer 4

23 pairs of chromosomes (46 in total) in regular cells; 23 chromosomes in reproductive cells

Question 5

How many chromosomes are from each parent?

Answer 5

23 from each parent

Question 6

When does conception occur?

Answer 6

When the ovum/egg and sperm come together; When the ovum/egg is fertilized by the sperm

Question 7

What is the difference between a dominant vs. recessive gene?

Answer 7

Dominant genes are the more powerful trait in a person while recessive genes are the weaker trait in a person. You need only 1 dominant gene for the trait to be expressed, whereas you need 2 recessive genes for the trait to be expressed.

Question 8

What is a carrier gene? Give one example.

Answer 8

A carrier gene is a recessive gene that is not visible. One example of a carrier is someone with one cystic fibrosis gene that will not have cystic fibrosis but will give cystic fibrosis to their child if the other parent also has the cystic fibrosis gene.

Question 9

What is a sex linked gene? Give one example.

Answer 9

A sex-linked gene is when a mother passes a recessive gene down to her son on her X gene. One example of a sex linked gene is when a mom has the gene for color-blindness and passes it on to her son, even though the gene is not expressed for her.

Question 10

What is the purpose of Genetic Counseling?

Answer 10

The purpose of genetic counseling is to identify the likelihood of passing certain genetic diseases or disorders onto your children. It is done by evaluating family history and medical records, ordering genetic tests, and evaluating the results of the investigation. The best time to see a genetic counselor is before getting pregnant.

Question 11

Achondroplasia: definition, 2 symptoms, and life expectancy

Answer 11

Definition: A bone growth disorder that causes disproportionate dwarfism
Symptoms: Short in stature, normal sized torso, short limbs
Life expectancy: Can be fatal if the person has homozygous achondroplasia but lifespan is normal for other people with achondroplasia

Question 12

Cystic fibrosis: definition, 2 symptoms, and life expectancy

Answer 12

Definition: A life-threatening disorder that causes severe damage to the lungs and digestive system
Symptoms: Thick mucus, trouble breathing, more prone to diseases
Life expectancy: Most people with cystic fibrosis live into their 20s-30s but some are living into their 40s-50s

Question 13

Down syndrome: definition, 2 symptoms, and life expectancy

Answer 13

Definition: A genetic disorder caused when an abnormal cell division results in extra genetic material from Chromosome 21
Symptoms: Distinct facial features, heart problems
Life expectancy: Average life expectancy of someone with down syndrome is 60 years

Question 14

Hemophilia: definition, 2 symptoms, and life expectancy

Answer 14

Definition: A bleeding disorder that slows the blood clotting process
Symptoms: Uncontrollable bleeding, joint pain, large and frequent bruising
Life expectancy: Life expectancy for men with hemophilia varies depending on the quality of medical care they can receive, but the average life expectancy is about 10 years shorter than it is for the general male population

Question 15

Progeria: definition, 2 symptoms, and life expectancy

Answer 15

Definition: An extremely rare and progressive genetic disorder that causes children to age rapidly
Symptoms: Slowed growth, hair loss, thinning and wrinkled skin
Life expectancy: The average life expectancy for someone with progeria is about 13-14 years, but some people have been able to live into their 20s

Question 16

Sickle cell disease: definition, 2 symptoms, and life expectancy

Answer 16

Definition: An inherited disease in which red blood cells are shaped like a sickle or crescent
Symptoms: Anemia, frequent infections, swelling of hands and feet
Life expectancy: The life expectancy of people with sickle cell disease is about 54 years

Question 17

Tay Sachs: definition, 2 symptoms, and life expectancy

Answer 17

Definition: A rare inherited disorder that progressively destroys nerve cells in the brain and spinal cord
Symptoms: Loss of motor skills, exaggerated startle reaction to loud noises, seizures and paralysis
Life expectancy: Most children with Tay Sachs only live to about 2-4 years old

Question 18

Turner Syndrome: definition, life expectancy, 2 symptoms

Answer 18

Definition: A genetic condition in which a female does not have the usual pair of two X chromosomes
Symptoms: Short stature, broad chest, widely-spaced nipples
Life expectancy: Life expectancy for women with Turner syndrome is slightly reduced. On average, the life expectancy of people with Turner syndrome is up to 13 years shorter than that of the general population.

Question 19

What does IVF stand for? What is the process?

Answer 19

IVF stands for In-Vitro Fertilization

The process of IVF is:
- Production of eggs are stimulated by hormone therapy
- Eggs are retrieved from the ovary
- Sperm samples are provided
- Eggs are sperm are combined and fertilized
- Fertilized eggs are reintroduced into uterus

Question 20

What does ICSI stand for? What is the process?

Answer 20

ICSI stands for Intra-Cytoplasmic Sperm Injection

The process of ICSI is:
- A single sperm is drawn into a micro-needle
- The sperm is directly injected into the mother’s egg

Question 21

What is a zygote?

Answer 21

A cell that is formed when a sperm fertilizes an egg (ovum)

Question 22

What is the difference between a monozygote and a dizygote?

Answer 22

Identical vs fraternal
A monozygote is 1 fertilized ovum that split into 2 identical cells while a dizygote is 2 different ovums that were fertilized with 2 different sperm

Question 23

What is considered a multiple birth?

Answer 23

2+ babies are born at the same time

Question 24

What are conjoined twins and the two theories on how they occur? What is the difference in the two theories?

Answer 24

Identical twins that are joined in utero (share one or more organs)

The 1st theory is that the fertilized egg split partially and the 2nd theory is that the fertilized egg split completely but adhesive molecules in the 2 eggs attracted each other and fused the eggs together again

Question 25

Why are more and more twins and multiple births occurring? What is the leading factor?

Answer 25

More and more twins and other multiple births are occurring due to fertility treatments. Many fertility treatments give women hormones to release multiple eggs at one time, allowing multiple eggs to be fertilized at or around the same time. IVF, a well-known fertility treatment, implants multiple fertilized eggs in a mother’s uterus, increasing the chance that multiple babies will grow.

Question 26

What are the risks for mom and babies when there are multiple births?

Answer 26

Mother:
- Preterm birth
- Placental problems
- Toxemia
- Hemorrhage
Kids:
- Preterm birth
- Placental problems
- Cerebral palsy
- Learning disabilities
- Blindness
- Developmental delays
- Mental disabilities

Question 27

What can increase the odds of a woman having twins? List two.

Answer 27

• If the woman has already had twins
• If the woman is older

Question 28

Why can cousins be half- siblings?

Answer 28

If their mom and aunt are identical twins, they’ll pass down the same DNA and their kids will therefore be half-siblings

Question 29

What are mirror image twins?

Answer 29

Identical twins with reverse asymmetric features (Ex: one is right-handed while the other is left-handed)

Question 30

What part of identical twins is NOT identical?

Answer 30

Their fingerprints

Question 31

What is a parasitic twin?

Answer 31

• The smaller and less developed member of an unequal conjoined twin that is often a mass of tissue attached to or within the larger twin
• Can have teeth, limbs, etc. but does not have a brain