Genetics Pt.1 Flashcards
(55 cards)
What are the two types of sex cells created in gametogenesis?
Oogenesis and Spermatogenesis
Oogenesis refers to the formation of ova (egg cells) and spermatogenesis refers to the formation of sperm cells.
How many chromosomes are in a human sex cell?
23
Human sex cells (gametes) contain half the number of chromosomes found in somatic cells.
What is the lifespan of a sperm cell?
3-5 days
Sperm cells typically have a lifespan of about 3-5 days once they are ejaculated.
How many viable cells are created during spermatogenesis?
Four sperm cells
Each spermatocyte undergoes meiosis to produce four viable sperm cells.
How many non-viable cells are created during oogenesis?
Three polar bodies
In oogenesis, one viable egg is produced along with three non-viable polar bodies.
Where does oogenesis occur in the human body?
Ovaries
Oogenesis takes place in the ovaries of females.
What hormone starts the development of oogenesis?
Estrogen / FSH
Follicle-stimulating hormone (FSH) along with estrogen initiates the development of gametes.
How often does spermatogenesis occur?
Continuously after puberty
Spermatogenesis begins at puberty and continues throughout a male’s life.
How does the process of meiosis mature the cell?
Reduces chromosome number and creates mature gametes
Meiosis involves two rounds of division, resulting in haploid cells that can participate in fertilization.
What is the duration of spermatogenesis?
74 days
It takes approximately 74 days for spermatogenesis to complete from start to finish.
What triggers ovulation?
Estrogen
The surge in estrogen levels leads to the ovulation process in oogenesis.
Fill in the blank: During oogenesis, the first meiotic division produces _______.
Ootid
The ootid is the result of the first meiotic division in oogenesis.
True or False: Spermatogenesis produces one viable sperm cell and three polar bodies.
False
Spermatogenesis produces four viable sperm cells, not polar bodies.
What is a karyotype?
Photographic inventory of an individual’s chromosomes
A typical karyotype shows 22 pairs of autosomes and 1 pair of sex chromosomes.
How many pairs of autosomes are typically found in a karyotype?
22 pairs
Autosomes are chromosomes that are not involved in determining the sex of an organism.
What are the two types of sex chromosomes in a typical human karyotype?
X and Y for males; X and X for females
Males have XY sex chromosomes, while females have XX.
What is nondisjunction?
Errors in meiosis when chromosomes fail to separate properly
This results in gametes with more or less than the haploid number of chromosomes.
What happens during nondisjunction in Meiosis I?
Homologous chromosomes fail to separate
This leads to gametes with an abnormal number of chromosomes.
What happens during nondisjunction in Meiosis II?
Sister chromatids fail to separate
This also results in gametes with an abnormal number of chromosomes.
What is monosomy?
Having only 1 copy of a particular chromosome where there should be a homologous pair
This results in a total of 45 chromosomes instead of the normal 46.
What is trisomy?
Occurs when there are 3 chromosomes in place of one homologous pair
This results in a total of 47 chromosomes.
Why are there more types of trisomy disorders than monosomy disorders?
Monosomy die early in life; trisomy is more common
Trisomy conditions often lead to viable pregnancies, whereas monosomy typically results in early miscarriage.
Is it more beneficial to have a nondisjunction error in Meiosis I or Meiosis II? Why?
Meiosis II is more beneficial because there are two viable cells
In Meiosis I, the error affects all resulting gametes, while in Meiosis II, only half are affected.
Fill in the blank: A typical karyotype shows 22 pairs of ______ and 1 pair of ______.
autosomes; sex chromosomes
