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Genetics > Week 2 > Flashcards

Week 2 Flashcards

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Biology 101 flashcards
1
Q

What does the P value really mean?

A

The P value is the probability of a departure form the null expectation that is greater than or equal to what was observed

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2
Q

Autosomal Inheritance in Humans

A

Transmission of genes carried on autosomes

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3
Q

What is an autosome

A

Chromosomes found in both males and females

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4
Q

Pattern of inheritance for autosomal dominant traits

A
  • Equal or similar frequency in males and females
  • Each individual with the trait has at least one parent with the trait
  • Either sex can transmit the trait to an offspring
  • Even if both parents have the trait, they may produce offspring who do not have it
  • Parents with a dominant phenotype that produce offspring with recessive phenotype must be heterozygous
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5
Q

Pattern of Inheritance for autosomal recessive traits

A
  • Equal frequency in males and females
  • If both parents have the trait, all offspring also will have it
  • The trait is often not seen every generation but frequently seen among siblings in the same generation
  • Unaffected parents of offspring with a recessive phenotype must be heterozygous
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6
Q

Diploid- Dominant life cycle

A

Majority of time spent as a diploid, Short period of time spent as haploid (gamete)
- Humans

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7
Q

Haploid-Dominant Life Cycle

A
  • Spend majority of life cycle as haploid
  • Most fungi and some unicellular eukaryotes
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8
Q

Species with blended diploid-dominant and haploid-dominant life cycles

A
  • Some algae and all plants have multicellular diploid (sporophyte) and haploid (gametophyte) life stages
  • In seeded plants, the gametophyte stage is only a few cells; the female gametophyte is contained within the flower
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9
Q

Cell Division

A

Tightly regulated process
- Too little prevents appropriate development and growth
- Too much leads to cancer, morphological anomalies and death

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10
Q

Mitotic Cell Cycle

A
  • M phase: Cell division occurs
  • Interphase: Longer period between cell divisions, including chromosome replication
  • G0: Cell division is arrested; cell remains specialized but no longer divides and eventually dies (apoptosis)
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11
Q

Stages of interphase

A
  • G1: Active gene expression and cell activity; preparation for DNA synthesis
  • S Phase: DNA replication and Chromosome duplication
  • G2: Preparation for cell division
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12
Q

Nucleolus

A

Where ribosome subunits are assembled

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13
Q

Centrosome

A

An organelle where spindle fibers form, that contains two microtubule structures called centrioles

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14
Q

Kinetochore

A

A disc-shaped structure where spindle fibers attach to pull sister chromatids apart

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15
Q

Prophase

A

Chromosomes condense

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16
Q

Prometaphase

A

Microtubules attach to chromosomes; nuclear membrane breaks down

17
Q

Metaphase

A

Chromosomes align on the metaphase plate

18
Q

Anaphase

A

Sister chromatids seperate

19
Q

Telophase

A

New nuclear membranes form

20
Q

Cytokinesis

A

The process by which the daughter cells separate

21
Q

Purpose of cell cycle checkpoints

A
  • Loss of cell cycle control is a major cause of cancer
  • Failure of checkpoint leads to programmed cell death (apoptosis)
22
Q

Cell Cycle Check points

A
  • G1 Checkpoint: Pass if cell size is adequate, nutrient availability is sufficient, and growth factors are present
  • S-Phase Checkpoint: Pass if DNA replication is complete and has been screened to remove base-pair mismatch or error
  • G2 Checkpoint: Pass if cell is adequate and chromosome replication is successfully completed
  • Metaphase Checkpoint: Pass if all chromosomes are attached to mitotic spindle
23
Q

Meiosis

A
  • Begins with diploid precursor cell that was generated by mitosis
  • Chromatids are then duplicated, but remain connected to each other at the centromere
  • The first round of cell division occurs (meiosis I), which results in each homologous chromosome becoming isolated in a different cell
  • The second round of cell division occurs (Meiosis II), which results in each chromatid becoming isolated in a different cell (gametes)
24
Q

What three major events occur in Meiosis I

A
  1. Homologous chromosome pair
  2. Crossing over (recombination) occurs
  3. Homologous chromosomes separate to daughter cells
25
Q

Meiosis: Prophase I

A

Homologous chromosomes pair (synapsis) and recombine

26
Q

Meiosis: Metaphase I

A

Pairs of homologous chromosomes align at the metaphase plate

27
Q

Meiosis: Anaphase I

A

Chromosomes separate; sister chromatids remain attached

28
Q

Meiosis: Telophase I

A

The nuclear membrane reforms; Cleavage furrow appear

29
Q

Meiosis: Cytokinesis

A

The process by which cells seperate

30
Q

Meiosis II

A

Separates sister chromatids into separate daughter cells

31
Q

Recombination

A
  • Occurs between non-sister chromatids of homologous chromosomes
  • Occurs prior to homolog separation during meiosis I
32
Q

The Synaptonemal Complex

A

A protein structure that forms between homologous chromosomes during meiosis I in eukaryotes
- Mediates recombination

33
Q

How does meiosis relate to the law of segregation?

A

Homolog separation in meiosis II is the biological basis of segregation

34
Q

How does meiosis relate to the law of independent assortment?

A

In meiosis one, there are alternative combination of which of the homologous chromosomes goes into each gamete

35
Q

Differences in Oogenesis and Spermatogenesis

A
  • Each miotic cell division of oogenesis results in 1 egg + 2 (or three) polar bodies (unequal cell division)
  • Each cell division of spermatogenesis results in four sperm cells (equal cell division)
    -Eggs are non-motile, sperm is motile
  • Growth phase in spermatogenesis is short (about 70 days), long in oogenesis (years)
  • Millions of sperm are produced each day
  • One egg is produced each mensural cycle, 1 ejaculate contains 200-300 million sperm
36
Q

Oogenesis in Humans: Numbers of Oocytes throughout development

A
  • Primary oocytes are established in female fetuses by 20 weeks after fertilization
  • At this point, there are 7 million primary oocytes
  • By birth, the number of primary oocytes decreases due to degeneration to 1-2 million (by puberty there are 60,000 - 80,000)
  • About 500 mature oocytes are produced during a woman’s life
37
Q

Oogenesis in humans: formation of an egg

A

IN UTERO
- Oogonium undergoes mitosis to become primary oocyte (which is stuck in prophase I)
AFTER PUBERTY
- Meiosis I occurs forming secondary oocyte and first polar body
- Secondary oocyte undergoes meiotic arrest in metaphase II and ovulation occurs
- When fertilized meiosis II is induced creating fully developed egg and secondary polar body

38
Q

Types of zygosity

A
  • Homozygous: Alleles are same
  • Heterozygous: Alleles are different
  • Hemizygous: Only one allele (e.g men at most x-linked genes)
39
Q

What is a reciprocal cross?

A
  • Allows one to examine the effects of sex on phenotypes
  • Uses concept that males have only one X chromosome so they will express recessive phenotypes for x-linked genes even though they have only one recessive X-linked allele
  • Cross of a female with recessive phenotype and male with dominant phenotype and then compare results to cross of reverse

Genetics (18 decks)

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