Chapter 24 Flashcards
The genes for cystic fibrosis are located on chromosome number
7
Cystic fibrosis is a hereditary disease that causes scar tissue to form in several organs, from nucleotide positioning techniques, it has been correlated with chromosome 7
Name 3 things true of chromosomes
Contain DNA
Coated with histones
46 mitotic cells
Chromosomes become visible only when they are condensed during active division, they r comprised of DNA molecules coated with histone protiens
Huntington disease is associated with chromosome
4
Huntington’s disease is a neurological condition with seizures and psychological alterations, associated with chromosome number 4
When does the chromosome number reach 92
Before prophase
What term refers to the inheritance of traits that require 2 genes
Recessive
When a physician questions a patient about their family history, they are gathering evidence to construct a
Pedigree
How is familial hypercholesterolemia usually inherited
Incomplete dominance
High blood cholesterol has been linked to defective LDL liver receptors, inherited by incomplete dominance
Diseases that display different symptoms and signs for the same disease are displaying
Pleiotropy
Heterogeneity refers to the expression of a phenotype by many different genes
The the SRY gene causes expression of ? Chromosome gene
X
The sex determining gene on the Y chromosome causes expression of traits for sex on the X
What is an example of a codominant trait in humans
ABO blood groups
Codominance means that both alleles can be expressed. As in the blood type AB
Traits that are controlled by one or more genes and influenced by the influence by the environment are said to be
Multifactorial
When both genes and environment play a role in a trait it has many factors
The fact that a woman cannot generally grow a beard is because beard growth is a ? Trait
Sex-limited
Sex-limited traits occur in certain sexes, usually due to hormonal influence
The normal chromosome number is referred to as
Euploid
Eu means normal
The last pair of 23 chromosomes is referred to as the
Sex chromosomes
The 23rd pair of chromosomes is the X and/or Y chromosomes
Which chromosomes indicate a normal male fetus
XY
A normal male is XY. XX is female
Persons with dark skin who produce offspring with the same color have genes that are probably
Homozygous for melanin enzymes
Homozygous alleles are pairs of genes on two chromosomes, one from each parent, that contain the same information for a specific protein synthesis
Name 3 organ systems significantly affected by cystic fibrosis
Pulmonary
Gastrointestinal
Reproductive
Sickle cell genes are present in ?% of the American population with Central African ancestry
8%
About 8% of Americans with Central Africa ancestry have the sickle cell anemia gene but only 1 out of every 170 children develop sickle cell anemia
When will a person with sickle cell trait develop symptoms
Under hypoxia
During times when the oxygen tension is low, the red blood cells may sickle and distort, blocking capillaries, exercise may not be a sufficient provocation
The genes for the ABO blood types are
Codominant
The genes for the ABO blood antigens are co-dominant and appear on multiple allele chromosome position
Persons with blood type B have the ? Agglutinogens (antigen)
B
Since the ABO blood types are inherited as co-dominants, a person with phenotype B must have only agglutinogen (antigens) B on their erythrocyte membranes
What blood type could these parents NOT produce in their children, AO and BB
O
The final height of a child is determined by
Polygenic inheritance
The height of individuals or variations in skin tone is inherited in a polygenic pattern with many genes involved in complex arrangements, a child can be quite different from their parents
Name 3 things that affect the expression in an individual with a homozygous recessive trait
The health of the mother
Disease in the father
Diet
The expression of genes is an interaction among gene DNA potentials and the ability to allow development of traits, given the influence of environmental factors such as diet or health.
The result of meiosis is to produce
23 chromosomes
Traits only transferred from fathers to their sons are associated with the ? Chromosome
Y
Traits on the X chromosome may be given to males or females
What condition is NOT usually found in females
Duchenne dystrophy
The growth of facial hair is an example of
Sex-limited trait expression
What is the probability of there being a recessive gene in the gametes from a parents who is Aa (assuming a is recessive)
50%
If the parent cells contain the Aa genome, it is assumed that the genes will separate and assort randomly as A or a resulting in a 50% distribution
What offspring result from Aa and aa parents
Aa, Aa, aa, aa
If it is assumed that the genes separate with equal probability, then 2 of each Aa and aa must result
The inheritance of maleness is caused by a ? Chromosome pattern
XY
Chromosome pair number 23 is associated with sex determination while the other 22 are autosomal and code other factors, XX would be the karyotype for a female and XY is male
Which type of condition can only be passed from the father to his sons
Holandric
Sex-linked recessive traits are passed by the mothers to her sons.
Name 3 X-linked recessive conditions
Hemophilia A
Color Blindness
Optic atrophy
The condition ? Is characterized by a deficiency of plasma thromboplastin component (factor IX)
Hemophilia B
What term is correctly used to describe all Down’s people?
Aneuploidy
Down’s syndrome is an aneuploidy or abnormal chromosome pattern
The term for prenatal genetic testing sloughed-off fetal cells is called
Amniocentesis
Name 3 conditions are usually seen in Down’s syndrome
Kidney defects
Heart defects
Mental retardation
How many genes are believed to constitute the human genome
40,000
During which meiosis division is the number of chromosomes halved
During meiosis I
Name a recessive human trait
Hairless forearms
Name 3 things that contribute to increasing genetic variability
Meiosis
Cross-over
Having children with someone who is not a relative
Several variant forms of a gene for a given trait are called
Alleles
A person who can pass either a widow’s peak or straight hairline to the next generation is said to be ? For the hairline trait
Heterozygous
If a recessive trait, such as hemophilia, occurs more often in males than in females, it is because the gene for the trait is most likely carried on
The X chromosome
If a child contain a genes that is not found in either parent, then one of them is not the biological parent
T or F
True
Gene identification techniques are sufficiently precise at this time to prove that someone is not a parent beyond a reasonable doubt
Traits such as skin pigment are totally governed by inheritance
T or F
False
Environmental factors influence the expression of genes such as the effect of sunlight on dispersion of melanin and darkness of the skin
Gene therapy has not been completely successful at this time
T or F
True
Although medical research is making great progress, no disease has been cured by genetic replacement at this printing
All forms of gene therapy changes cannot be inherited
T or F
True
Some theoretical applications of gene therapy will involve fundamental changes in the genome at the level of the zygote
Fetal stem cells have no value over bone marrow in gene therapy research
T or F
False
Fetal cells have tremendous value because of their multipotential capabilities
A younger women has a higher risk of a Down’s conception than one who is older
T or F
False
The greater the women’s age, the higher the risk for having a baby with Down’s
Chorionic villus sampling is less invasive than amniocentesis
T or F
False
Chorionic villus sampling carries a higher risk of miscarriage
Gene therapy using the liver can be used to prevent heart disease
T or F
True
Gene’s can be inserted for Person’s lacking LDL receptors in the liver thereby reducing the risk of LDL-induced coronary artery cholesterol plaque formation
Viruses are the usual cause of brain tumors such as gliomas
T or F
False
Actually viruses can be theoretically inserted in brain glioma tumors as a treatment
The phenomenon of incomplete dominance will result in the meiosis of cells with two forms of a particular gene
T or F
True
Incomplete dominance occurs when a particular gene such as for hemoglobin, has two distinct allele forms in which each pair may be homozygous or Herterozygous
Males always determine the sex of a fetus
T or F
True
Only the sperm cells contain either a Y or X chromosome, the oocytes are all X
A male with color blindness cannot have a daughter who is color blind because it is a X linked recessive
T or F
False
Mainly males exhibit x linked disorders because their single x gene cannot be masked by another x, therefore making the recessive x appeardominant, a female who is homozygous for color blindness gene will express the trait, although it is rare
It is possible for human cells to have more than 46 chromosomes
T or F
True
Because of the phenomenon of non-disjunction and other abnormal processes, many individuals 48 or more chromosomes such ad a XXYY pattern
The disintegration of chromosomes during meiosis is called nondisjunction
T or F
False
Nondisjunction is when chromosomes remain attached at the centromere
Older women carry a greater chance of having a child with trisomy 21 than a younger mother
T or F
True
Facts show that the risk of trisomy 21 increase dramatically with maternal age
Persons with Turner’s syndrome have male chromosomes but have a female appearance
T or F
False
Turner’s syndrome is having only one sex chromosome, the X
Only the sperm have the ability to determine the sex of the offspring
T or F
True
The egg always contributes an X chromosome
All genetic abnormalities are inherited
T or F
False
Mutations can occur during a lifetime
Sex-linked genes are those associated with chromosomes X or Y
T or F
True
Sex-limited means coming from the X or Y chromosome
Males and females have equal chances of inheriting X-linked disorders
T or F
False
Males are at higher risk of X linked disorders because they only receive one X chromosome
All Preston’s with Down’s syndrome display profound mental retardation
T or F
False
Not all people with Down’s syndrome are retarded, some display perfectly normal or even higher intelligence
The genes of an individual will always be different from those of the parents
T or F
True
Since there are random variations in the DNA base sequences, the offspring resemble but are always slightly unique because of these new combinations and interactions with the environment
All birth defects are genetic and inherited
T or F
False
Birth defects are caused by teratogens from the environment
