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35 Cards in this Set
- Front
- Back
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What is a Barr Body?
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The inactive x-chromosome in a female cell
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What is Imprinting?
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when a gene is expressed either active or inactive in the embryo depending on whether it derived from the mother or the father
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What is a Polar Body?
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Cells containing only one x-chromosome or a haploid nucleus which takes no part in the embryo development
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What is Exclusion?
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The loss of DNA in the somatic cells not the germ cells.
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What is Polydactyly?
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The occurance of extra digits on hands or feet.
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What is the Acrosomal Reaction?
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The release of enzymes and proteins from the acrosomal vesicle of the sperm head that occurs once a sperm binds to the surface of the egg. It helps the sperm bind to the surface of the egg and penetrate the outer layer.
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What is Klinefelter Syndrome?
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Individuals have 2-X-chromosomes and 1-Y-chromosome but are MALE. (XXY) infertile males with small testes
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What is Turner Syndrome?
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Individuals have 1-X-chromosomes and are FEMALE. (XO) females dont produce eggs
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What is Trisomy21?
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Down Syndrome. Chromosomal disorder cause by the presence of an extra 21-st chromosome or part of it. There are 3 21-st chromosomes instead of 2.
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What is an Extodermal ridge?
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A critical component of limb growth which is essential for both outgrowth of the limb as well as the correct proximal-distal patterning.
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What is SRY?
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Sex Determinging Region of Y chromosome. A gene on the Y chromosome which tells the gonad to turn to testes.
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Draw a sperm and name the main parts to it.
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Head, Acrosomal Vesicle, Nucleus, Midpiece, Mitochondria, Tail, Flagellum
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Draw a cross-section of a mouse testis and label main parts.
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Lumen, Sertoli cell, basement membrane.
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Draw a follicle and label main parts.
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Thecal cells, granulosa membrane, granulosa cells, antrum, oocyte.
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What are the key steps in fertilization?
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- Sperm has to find oocyte
- Sperm has to degrade protective layer of follicle - Sperm has to enter oocyte |
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What hormone promotes male gonad development in humans?
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Testosterone
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Which species have environmental gender dependency?
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Alligator, some Turtles
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Explain how the expression from the Drosophilla Sex-Lethal early promoter is regulated.
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When 2-X-chromosomes are present the early promoter of SXL is activated and produces SXL. Maintenance promoter is active in both males and females and early promoter gets turned off. SXL RNA splices only if SXL protein is present which is only in females.
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How does the sea urchin egg prevent polyspermie?
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The egg's plasma membrane quickly depolarizes. The electrical membrane potential across the plasma membrane goes from -70mV to +20mV
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Describe how the worls in an Arabidopsis flower are specified.
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There are 4 worls.
worl 1 contains 4 sepals worl 2 contains 4 petals worl 3 contains 6 stamen (male reproductive organs) worl 4 contains 2 carpel (female reproductive organs) |
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How many axes does a Drosophilla wing have? How many axes does a chicken wing have?
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Drosophilla wing has 2 axes (A-P, D-V)
Chicken wing has 3 (A-P, P-D, D-V) |
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Why can a mouse and a rat not reproduce together?
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They have different number of chromosomes. Mouse has 40 rat has 41.
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Describe how Sex-Lethal protein leads to the female-specific form of Double-Sex.
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Sex-Lethal controlls the expression of the transformer gene. In the presence of SXL protein transformer RNA is spliced and this along with transformer 2 leads to the female form of the double sex protein being made.
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Name 3 human hormones and describe what they do.
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1. Growth Hormone - protein hormone that is essential for post embryonic growth. Secreted by pituitary gland.
2. Testosterone - Produced by testis and required for production of male reproductive parts. 3. Estrogen - Produced by ovaries. The primary female sex hormone. regulates menstrual cycle. |
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What is the difference between protein hormone and endocrine hormone signaling?
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Endocrine - receptors are located inside the cells within the cytoplasm. In order to bind they need to cross cell membrane. once hormone combines to receptor they move across nuclear membrane into nucleus where they bind to DNA.
Protein - receptor is embeded in plasma membrane at surface of cell. once bound a cascade of secondary effects is triggered in cytoplasm. |
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How is dosage compensation achieved in :
Mammals, Drosophila, C. Elegans |
Mammals - inactivating one of the X chromosomes in females after the blastocyst has implanted in uterine wall.
Drosophila - transcription of the X chromosome in males is increased nearly 2 fold. C. Elegans - reducing the level of X chromosome expression in XX animals to that of the single X chromosome in XO animals |
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How are germ cells specified in:
Mammals, Drosophila, C. Elegans |
Mammals - germ plasm specified by Oskar at posterior end of egg
Drosophila - have no germ plasm C. Elegans - germ plasm is characterized by polar granules and PIE 1 protein, and segregates into P4 during cleaveage |
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What is the signal/event upon which the mammalian oocyte finishes meiosis?
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When sperm enters the egg and fuses with it. One of remaining pair of chromosomes gets ejected.
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Why are germ cells surrounded by somatic cells?
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Because somatic cells make up everything in the body besides the germ cells (sperm and egg). Somatic cells form the body of an organism.
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Why may a zygote not be able to implant into the uterus?
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Sperm and egg DNA may not be compatible
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Explain the Lyon hypothesis.
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During early development one of the X-chromosomes in females gets turned off randomly. This occurs so that the female with 2-X-chromosomes doesnt have twice as many chromosome gene products as a male with only 1-x-chromosome.
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Major differences between Meiosis and Mitosis.
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Mitosis takes place in somatic cells, miosis takes place in gamete cells.
Mitosis divides a somatic cell in 2 daughter cells. Miosis cells produce 4 daughter cells. Mitosis can have either haploid or dipoloid # of chromosomes. Miosis contain only dipolid # of chromosomes. |
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What is the French Flag model and what does it predict?
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It represents the effect of a morphogen on cell differentiation. If you transplant the distal cell of a leg disc into the distal region of an antennae disc, you get flies with claws at the end of antennae.
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What happens if you starve a tadpole?
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It will stay dormant and not develop into an adult.
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How can you visualize the calcium wave of the fertilized mouse oocyte and why is this wave important.
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You can visualize it by injecting calcium indicator dye in the egg. Red florescence in presence of calcium. Calcium release is indicated by sperm entry and is both necessary and sufficient to initiate development.
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