Biology Chapter 14

Front 1

A chart which shows the relationships within a family is called ____________.

Back 1

pedigree chart

Front 2

Why can't some obvious human traits be traced to single genes?

Back 2

Because many human traits are determined by multiple genes or are influenced by both genetics and environmental factors. For example, both genetics and environment (nutrition and exercise) determine height.

Front 3

When chromosomes from photographed cells are pairted together by biologists, it is called a __________/

Back 3

karyotype

Front 4

Which chromosomes determine an individual's sex?

Back 4

sex chromosomes

Front 5

In humans 2 of the 46 chromosomes are sex chromosomes. The remaining 44 chromosomes are called _______________.

Back 5

autosomal chromosomes or autosomes

Front 6

Females have two copies of a large _____ chromosome.

Back 6

X

Front 7

Males have one ___ and one small ______ chromosome.

Back 7

X and Y

Front 8

Why are males and females born in a roughly 50:50 ratio?

Back 8

Because all human egg cells carry a single X chromosome (23,X). Half of all sperm cells carry an X chromosome and half carry the Y (23,Y) resulting in half of the zygotes being 46,XX and half being 46,XY.

Front 9

What does the Rh stand for in the Rh blood group?

Back 9

rhesus monkey where the single gene determining this blood group was discovered.

Front 10

Why is knowing a person's genetically determined blood group important?

Back 10

Because receiving a transfusion of the wrong blood type during a medical procedure can be fatal.

Front 11

What are the two alleles of the Rh blood group gene?

Back 11

positive and negative

Front 12

How many alleles are there for the ABO blood group?

Back 12

Three - I(A), I(B) and i .
A and B are codominant -- resulting in A, B, or AB blood types.
i is recessive ii = Blood type O

Front 13

If a person has a dominant allele for a genetic disorder, what happens?

Back 13

The genetic disorder is always expressed.
Achondroplasis (a form of dwarfism)
Huntington's Disease - no symptoms until 30s or older

Front 14

Name a disease caused by a codominant allele.

Back 14

sickle cell disease

Front 15

Name some disorders caused by autosomal recessive alleles.

Back 15

Tay-Sachs, PKU, cystic fibrosis, Albinism, Galactosemia

Front 16

Explain how a small change in DNA causes the genetic disorder Cystic Fibrosis.

Back 16

On chromosome 7 a recessive allele is missing 3 DNA bases which removes one amino acide from a protein. The CTFR protein is responsible for transporting chloride ions and because of the damaged protein tissues in the body malfunction.

Front 17

How does a DNA change cause the genetic disorder sickle cell disease?

Back 17

The DNA base substitutes the amino acid valine for glutamic acid. The abnormal hemoglobin is less soluble causing molecules to stick together forming sickled cells.

Front 18

What is the relationship between sickle cell disease and malaria?

Back 18

In people who are heterozygous for the sickle cell allele, they are healthy and also are resistant to malaria. In areas of the world where malaria is more common, more people have the sickle cell allele. Since many african americans trace ancestry to west Africa which is a malaria prone region, the sickle cell allele is more common in that population.

Front 19

Is the sickle cell allele dominant or recessive?

Back 19

codominant

Front 20

How many base pairs of DNA are contained in a human diploid cell?

Back 20

More than 6 billion

Front 21

How much of chromosomes are made up of genes?

Back 21

Only about 2 percent

Front 22

How many bases does a gene have?

Back 22

the average human gene has about 3000 base pairs

Front 23

How many base pairs does the largest gene in the human genome have?

Back 23

More than 2 million

Front 24

What are the smallest human autosomes?

Back 24

Chromosomes 21 and 22

Front 25

Describe the make up of chromosomes 21 and 22.

Back 25

They both contain genes, some of which are important for human health including some that are related to genetic disorders. Parts of Chromosome 22 contain repetitive DNA that do not code for proteins. Parts of Chromosome 21 have no genes at all.

Front 26

What are sex linked genes?

Back 26

Genes located on the X or Y chromosome

Front 27

Where are the human genes associated with color blindness located?

Back 27

On the X chromosome

Front 28

Why is color blindness more common in males than females?

Back 28

Because males have just on X chromosome so all X-linked alleles are expressed in males even if recessive. To be expressed in females, there must be two copies of the allele, one on each of the two X chromosomes.

Front 29

Name two other X linked disorders.

Back 29

Hemophilia and Duchenne Muscular Dystrophy

Front 30

What happens to the extra X chromosome in females?

Back 30

One X chromosome is randomly switched off forming a Barr body in the nucleus

Front 31

If a cat's fur has three colors is it male or female?

Back 31

It must be female because the X chromosomes control color spots and different X chromosomes were switched off in different parts of the body.

Front 32

What is nondisjunction?

Back 32

When homologous chromosomes fail to separate in meiosis

Front 33

What is the result of nondisjunction?

Back 33

Abnormal numbers of chromosomes may find their way into gametes resulting in a disorder

Front 34

What is the most common form of trisomy?

Back 34

Down Syndrome involving 3 copies of chromosome 21

Front 35

How can prospective parents find out if they might be carrying recessive alleles for a genetic disorder?

Back 35

Genetic testing can look for these abnormalities

Front 36

What is DNA fingerprinting?

Back 36

Analysis of sections of DNA that have little or no function but vary widely from one individual to another to allow identification through blood, sperm and even hair strands

Front 37

What is the Human Genome project?

Back 37

An ongoing effort to analyze the human DNA sequence

Front 38

What is gene therapy?

Back 38

Replacing an absent or faulty gene with a normal, working gene