Reproduction & Development Flashcards
What is crossing over?
Crossing over is when non-sister chromatids exchange alleles (different versions of genes).
During meiosis 1, homologous pairs line up, leading to them becoming tangled, creating tension on the DNA molecules which causes the chromatid to break and rejoin on the other chromosome.
What is independent assortment?
Independent assortment leads to the production of different combinations of alleles in daughter cells due to the random alignment of homologous pairs along the equator of the spindle during metaphase.
What happens during Prophase I?
DNA condenses and becomes visible as chromosomes. DNA replication has already occurred, so each chromosome consists of two sister chromatids joined together by a centromere. The chromosomes are arranged side by side in homologous pairs.
A pair of homologous chromosomes is called a bivalent.
What occurs during crossing over in Prophase I?
As the homologous chromosomes are very close together, the crossing over of non-sister chromatids may occur. The point at which the crossing over occurs is called the chiasma (chiasmata; plural).
What structural changes occur in Prophase I?
Centrioles migrate to opposite poles, and the spindle is formed. The nuclear envelope breaks down, and the nucleolus disintegrates.
What happens during Metaphase I?
The bivalents line up along the equator of the spindle, with the spindle fibres attached to the centromeres.
What occurs during Anaphase I?
The homologous pairs of chromosomes are separated as microtubules pull whole chromosomes to opposite ends of the spindle. The centromeres do not divide.
What happens during Telophase I?
The chromosomes arrive at opposite poles. Spindle fibres start to break down. Nuclear envelopes form around the two groups of chromosomes, and nucleoli reform. Some plant cells go straight into meiosis II without reformation of the nucleus in telophase I.
What is Cytokinesis?
This is when the division of the cytoplasm occurs. Cell organelles also get distributed between the two developing cells. The end product of cytokinesis in meiosis is two haploid cells.
What is the second division of meiosis called?
Meiosis II
Is there an interphase between meiosis I and meiosis II?
No, there is no interphase between meiosis I and meiosis II, so the DNA is not replicated.
How does meiosis II compare to mitosis?
The second division of meiosis is almost identical to the stages of mitosis.
What happens during Prophase II?
The nuclear envelope breaks down and chromosomes condense. A spindle forms at a right angle to the old one.
What occurs during Metaphase II?
Chromosomes line up in a single file along the equator of the spindle.
What happens during Anaphase II?
Centromeres divide and individual chromatids are pulled to opposite poles, creating four groups of chromosomes that have half the number of chromosomes compared to the original parent cell.
What occurs during Telophase II?
Nuclear membranes form around each group of chromosomes.
What is the final step of meiosis II?
Cytokinesis occurs, where the cytoplasm divides as new cell surface membranes are formed, creating four haploid cells.
What is the chromosome count in the resulting cells after meiosis II?
The cells contain the same number of centromeres as they did at the start of meiosis I but now only have half the number of chromosomes.
What are the main components of the reproductive system?
The reproductive system consists of the ovaries, fallopian tubes, uterus, vagina, external genitalia, and breasts.
What is the function of the vagina?
The vagina extends from the cervix to the external genitalia and aids conception by receiving the penis and semen during sexual intercourse.
What is the structure of the vagina?
The vagina is made up of smooth muscle and a mucosal inner lining.
What is the primary function of the uterus?
The uterus is responsible for the growth of an implanted fetus.
What are the three layers of the uterus?
The three layers of the uterus are the perimetrium, myometrium, and endometrium.
What is the perimetrium?
The perimetrium lines alongside the peritoneum.
What is the myometrium?
The myometrium is the muscular wall of the uterus, allowing contractions during childbirth and menstruation.
What is the endometrium?
The endometrium is a specialized epithelial layer that adapts during the menstrual cycle.
What hormones do the ovaries produce?
The ovaries produce oestrogen and progesterone.
What do the ovaries release?
The ovaries release follicles which contain immature eggs.
What is the role of the fallopian tubes?
The fallopian tubes are responsible for the transportation of the immature eggs from the ovaries to the uterine lining.
What aids in the transportation of egg cells?
Cilia and mucous aid transportation and help maintain nourishment of the egg cells.
What are the four stages of the menstrual cycle?
The menstrual cycle consists of four stages: menstrual phase (day 1-5), follicular phase (day 1-13), ovulation phase (day 14), and luteal phase (day 15-28).
What is menopause?
Menopause is the biological process where a woman permanently stops having menstrual periods, signaling the end of their ability to naturally conceive.
What is perimenopause?
Perimenopause is the phase where hormone levels begin to fluctuate, periods become irregular, and symptoms of menopause, such as hot flushes, begin.
What are the causes of perimenopause?
Causes of perimenopause include early puberty, smoking, not giving birth, being underweight, and treatments such as chemotherapy, hormone medication, or reproductive surgery.
How is menopause defined?
Menopause is defined as when a woman has not had a period for 12 months.
What symptoms do women experience during menopause?
Women may experience symptoms such as hot flushes, night sweats, and vaginal dryness during menopause.
What is post menopause?
Post menopause is the phase where women may still experience symptoms, and with reduced oestrogen, there could be an increased risk of osteoporosis and heart disease.
What are the main components of the male reproductive system?
The male reproductive system consists of the penis, testes, scrotum, the male duct system, and prostate glands.
What is the primary function of the penis during sexual activity?
The penis is responsible for ejaculation of sperm during sexual activity.
What system is the penis a part of?
The penis is part of the genitourinary system.
What is the glans penis?
The glans penis is the most sensitive part of the penis.
What covers the glans penis?
The glans penis is covered in a layer of foreskin.
What type of tissue is found in the glans penis and shaft?
The glans penis and shaft contain erectile tissue.
What happens to erectile tissue during an erection?
Erectile tissue can fill with blood to enlarge and trigger an erection.
What are psychogenic causes of erections?
Psychogenic causes result from sexual thought, emotional reaction, or audio-visual stimulation, involving interaction from the temporal and frontal lobes plus the limbic system to trigger impulses to the spinal nerves to trigger an erection.
What are the risks of acting on psychogenic causes?
Acting on psychogenic causes (e.g., masturbating) can increase the risk of erectile dysfunction, premature ejaculation, and altered perception about sex, which can lead to increased risk of sexual abuse, rape, and reduced sexual confidence.
What is reflexogenic erection?
Reflexogenic erection is physical stimulation resulting in a spinal reflex, known as the bulbocavernosus reflex.
Can erections occur during sleep?
Yes, erections can also be sleep-induced during the REM sleep phase.
What is the primary function of the testes?
The testes are responsible for maintaining sperm life by regulating temperature.
Where are the testes located and why?
The testes hang outside the body to help maintain a temperature 3 degrees lower than the core temperature within the scrotum.
How does the scrotum respond to colder conditions?
The scrotum can pull the testes closer in response to colder conditions.
What causes the testes to move closer or further away from the body?
This is due to the contraction of the cremaster muscle or the relaxation of the muscles.
What happens to the testes during warmer conditions?
The muscles can relax to encourage the testes to hang lower during warmer conditions.
What is the starting point of the Male Duct System?
The Male Duct System starts from the epididymis.
Where does the Male Duct System end?
The Male Duct System ends in the urethra.
What is the function of the epididymis?
The epididymis sits above the testes where sperm can mature before ejaculation occurs.
What action moves mature sperm cells into the vas deferens?
During sexual activity, peristaltic action moves mature sperm cells into the vas deferens.
What happens to sperm in the prostate gland?
In the prostate gland, prostatic fluid mixes with sperm to form semen.
Where is semen produced?
Semen is produced in the seminal vesicle.
What is the role of prostatic fluid?
Prostatic fluid provides an alkalotic environment for sperm to combat the acidic conditions within the vaginal tract.
How does prostatic fluid affect the urethra?
Prostatic fluid also neutralizes the urethra after being exposed to urine.
What are the four stages of sexual arousal and intercourse?
The four stages are arousal, plateau, orgasm, and resolution.
What are safe sex considerations regarding contraception?
Use of contraception such as condoms and implants helps to reduce the risk of pregnancy.
What types of condoms are available?
Condoms can be thick, thin, ribbed, and latex-free depending on individual needs.
What hygiene practices should be followed for oral sex?
Effective hygiene and the use of dams or condoms are important. Be aware of open sores or cuts.
What should be avoided before oral sex?
Avoid brushing your teeth just before oral sex due to the risk of bleeding gums.
What should be considered for fingering?
Be aware of cuts, as they can increase STD transmission. Good hand and nail hygiene is important.
What hygiene practices should be followed for anal sex?
Effective hygiene and risk of faecal contamination should be considered.
What can promote safer anal sex?
Anal douching and the use of strong condoms with water-based lubrication can promote safer anal sex.
Why is lubrication important for anal sex?
Lubrication prevents permanent damage to the anal passage, which leads to a higher risk of STD transmission.
