Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HAN 202 > Chapter 29: Heredity > Flashcards

Chapter 29: Heredity Flashcards

1
Q

Genetics

A

study of the mechanism of hereditary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Human Genome Project (1990-2003)

A

has determined human DNA sequence, which can aid in genetic research and genetic screening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Diploid number of chromosomes

A

Diploid number= 46 (23 pairs of homologous chromosomes)= 2n

  • In all cells except gametes -
  • > Haploid number= 1n
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

1 pair of sex chromosomes determines the genetic sex

A 
XX= female
XY= male
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

22 pairs of autosomes guide the expression of most other traits

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

gene pairs (alleles)

A
  • alleles are genes that occur at same LOCUS (location) on homologous chromosomes
  • homozygous: alleles controlling a single trait are the same (TT, tt)
  • heterozygous: alleles for a trait are different (Tt)
  • dominant: an allele that masks or suppresses its (recessive) partner
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Genetics- gregor mendel

A
  • Austrian monk (1822)
  • Teacher, in charge of monastery garden
  • Two types of pea plants – tall and short
  • Self pollinating vs cross pollinating

*cross pollinating a tall and short plant produces all tall plants, but next generation will produce 3 tall and 1 short

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

genotype

A

the genetic makeup (Tt)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

phenotype

A

the way the genotype is expressed (tall pea plant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

sexual sources of genetic variation

A
  1. chromosome segregation and independent assortment
  2. crossover of homologous
  3. random fertilization of eggs by sperm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. segregation and independent assortment
A
  • > Independent assortment: during gametogenesis, maternal and paternal chromosomes are randomly distributed to daughter cells, (which allele a gamete recieves for gene A has no bearing on the allele it recieves for gene B)
  • occurs during metaphase of meiosis

-> segregation: distribution of 2 alleles for a trait to different gametes during meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

independent assortment

A

during gametogenesis, maternal and paternal chromosomes are randomly distributed to daughter cells,
*occurs during metaphase of meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

segregation

A

distribution of 2 alleles for a trait to different gametes during meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

segregation and independent assortment

A

-the number of gamete types= 2^n, where n is the number of homologous pairs

ex: 2^3= 8 (2x2x2)
in a man testes, 2^n= 2^23= 8.5 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. crossover and genetic recombination
A
  • > genes on the same chromosome are linked
  • > chromosomes can cross over, forming a chiasma, and exchange segments
  • > crossover occurs during prophase of meiosis
  • > recombinant chromosomes have mixed contributions from each parent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

karyotype

A

diploid chromosomal complement displayed in homologous pairs

17
Q

homologous chromosomes synapse during prophase of meiosis 1. Each chromosome consists of 2 sister chromatids

A

true

review slides 14-17

18
Q

random fertilization

A

adds to genetic variation because any sperm can fuse with any ovum (unfertilized egg)

19
Q

types of inheritance

A
  • most traits are determined by multiple alleles or by the interaction of several gene pairs
  • dominant-recessive inheritance
  • multiple-allele inheritance
  • polygene inheritance
20
Q

dominant recessive inheritance

A
  • reflects the interaction of dominant and recessive alleles
  • punnett square: predicts the possible gene combinations resulting from the mating of parents of known genotypes

traits:

  • attached earlobes (unattached= dominant)
  • roll tongue
  • dimples
  • freckles
  • curly hair
  • cleft chin
  • widows peak
21
Q

dominant disorders

A

are uncommon because many are lethal and result in death before reproductive age

**exception: Huntington’s Disease is caused by a delayed action gene- person survives long enough to reproduce

22
Q

dominant recessive inheritance

A
  • most genetic disorders are inherited as simple recessive traits…. albinism, cystic fibrosis, and tay-sachs disease
  • heterozygotes are carriers who do not express the trait but can pass it on to their offspring
23
Q

incomplete dominance

A

-heterozygous individuals have an intermediate phenotype

  • example: sickling gene
  • SS= normal Hb is made
  • Ss= sickle cell trait (both aberrent and normal Hb are made); can suffer a sickle-cell crisis under prolonged reduction in blood O2
  • ss= sickle cell anemia (only aberrant Hb is made; more susceptible to sickle cell crisis)
24
Q

multiple allele inheritance

A
  • genes that exhibit more than 2 allele forms
  • ABO blood grouping is an example
  • 3 alleles (I^A, I^B, i) determine the ABO blood type in humans

I^A and I^B are codominant (both are expressed if present), and i is recessive

25
Q

sex-linked inheritance

A
  • inherited traits determined by genes on the sex chromosomes
  • X chromosomes bear over 1400 genes (many for brain function); Y chromosomes carry about 200 genes
  • more than 100 sex-linked disorders have been mapped to the X chromosome
26
Q

sex linked inheritance

A

X-linked genes are

  • found only on the X chromosome
  • typically passed from mothers to sons (e.g hemophilia or red-green color blindness)

***males have just 1 X chromosome, thus all X-linked alleles are expressed in males, even if recessive

27
Q

why are most calico cats female?

A

Coat color is determined by X chromosome
One X has allele for black spots
One X has allele for orange spots
Female cats can have a combination of black and orange spots, males (only one X) can have only one color

28
Q

polygene inheritance

A
  • depends on several different gene pairs at different locations acting in tandem
  • results in continuous phenotypic variation between 2 extremes
  • ex: skin color, eye color, height, metabolic rate, and intelligence
  • Skin color is controlled by 3 separately inherited genes, each existing in 2 allelic forms: A, a; B, b: C, c
29
Q

chromosomal disorders

A
  • if 2 copies of an autosomal chromosome fail to separate during meiosis, and individual may be born with 3 copies of a chromosome
  • down syndrome: 3 copies of chromosome 21
30
Q

phenocopies

A
  • > genotype: (excluding mutations) is unchanging
  • > phenotype: can be molded or changed (clay)
  • > phenocopies: environmentally produced phenotypes that mimic conditions caused by genetic mutations during embryonic development…. thalidomide babies
  • > environmental factors can influence genetic expression after birth
  • poor nutrition can affect brain growth, body development, and height
  • childhood hormonal deficits can lead to abnormal skeletal growth and proportions
  • getting a tan
31
Q

Beyond DNA: regulation of gene expression

A

3 levels of control are found in human genome

  • > first layer: protein coding genes
  • involves less than 2% of a cells DNA
  • DNA that is blueprint for protein synthesis
  • > second layer: small RNAs
  • found in non-protein-coding DNA
  • > third layer: epigenetic marks
  • stored in proteins and chemical groups that bind to DNA and in way chromatin packaged
32
Q

small RNAs

A

microRNAs (miRNAs) and short interfering RNAs (siRNAs)

  • act directly on DNA , other RNAs, or proteins
  • may silence genes or prevent their expression and appear to play a role in directing apoptosis during development

-> in future, RNA- interfering drugs may treat diseases such as age-related macular degeneration and Parkinson’s disease

33
Q

Epigenetic marks

A
  • info stored in the proteins and chemical groups bound to DNA
  • determine whether DNA is available for transcription or silenced. ‘if DNA is like the alphabet then epigenetic marks are like punctuation’
  • Epigenetics: study of heritable changes in gene expression. Change in phenotype without change in genotype
  • lifestyle can affect individual epigenetics:
  • pollution
  • diet
34
Q

extranuclear (mitochondrial) inheritance

A
  • not all DNA is located in cell’s nucleus
  • mitochondria contain 37 of their own genes, referred to as mitochondrial DNA (mtDNA)
  • mitochondria are transmitted to embryo by mother in cytoplasm of egg
  • errors in mtDNA are linked to rare disorders
  • usually problems associated with oxidative phosphorylation (cellular respiration)
  • some muscle and neurological problems, possibly alzheimers and parkinsons
35
Q

genetic screening, counseling, and therapy

A

-newborn infants are routinely screened for a number of genetic disorders: congenital hip dysplasia, imperforate anus, and other metabolic disorders

other examples:

  • screening adult children of parents with huntington’s disease
  • testing a woman pregnant for the first time after age 35 to see if the baby has trisomy-21 (down syndrome)
36
Q

carrier recognition

A
  • Two major avenues for identifying carriers of genes: pedigrees and blood tests
  • Pedigrees trace a particular genetic trait through several generations; helps to predict the future
  • Blood tests and DNA probes can detect the presence of unexpressed recessive genes
  • Tay-Sachs and Cystic Fibrosis genes can be identified by such tests
37
Q

fetal testing

A
  • Used when there is a known risk of a genetic disorder
  • Amniocentesis: amniotic fluid is withdrawn after the 14th week and fluid and cells are examined for genetic abnormalities
  • Chorionic villus sampling (CVS): chorionic villi are sampled and karyotyped for genetic abnormalities
38
Q

human gene therapy

A
  • Genetic engineering has the potential to replace a defective gene
  • Defective cells can be infected with a genetically engineered virus containing a functional gene (because they can enter the nucleus)
  • The patient’s cells can be directly injected with “corrected” DNA

HAN 202 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions