Genetics and Prenatal Development Flashcards

Question

Cytoplasm

Answer 1

Fluid that provides nutrients for the ova for first two weeks of fertilisation, until reaches uterus to begin drawing nutrients from mother.

Answer 2

After the chromosomes first split and replicate but before the cell divides, pieces of genetic material are exchanged between the alleles in each pair. Crossing over mixes the combinations of genes in the chromosomes, so that genetic material that originated from the mother and father (your grandparents) is rearranged in a virtually infinite number of ways.

Answer 3

Parent cell Lining up and crossing over Chromosome replication Cell division Cell division 2

Answer 4

The follicle consists of the ovum plus other cells that surround it and provide nutrients. About 14 days into a woman’s cycle, the mature follicle bursts and ovulation takes place as the ovum is released into the fallopian tube. The ovum is 2,000 times larger than a sperm because it contains so much cytoplasm. It is only during the first 24 hours after the ovum enters the fallopian tube that fertilisation can occur. It takes sperm from a few hours to a whole day to travel up the fallopian tubes, so fertilisation is most likely to take place if intercourse occurs in the 6 days leading up to and including the day of ovulation. Sperm can live up to 5 days after entering the woman’s body, but most do not last more than 2 days and pregnancy is much more likely on the day of ovulation.

Answer 5

The new cell formed from the union of the sperm and ova.

Answer 6

About 14 days into a woman’s menstrual cycle, an ovum is released into the fallopian tube. When fertilisation occurs, the 23 chromosomes from the ovum pair up with the 23 chromosomes from the sperm and a new cell, the zygote, is formed from the two gametes. The zygote’s 46 paired chromosomes constitute the new organism’s unique genotype, set once and for all at the moment of conception.

Answer 7

First trimester 1-2 weeks: Germinal period Zygote divides and forms blastocyst, which implants in uterus and begins forming amnion, placenta, and umbilical cord. 3-4 weeks: Embryonic period Three layers form: ectoderm, mesoderm, and endoderm. Neural tube develops and produces neurons. Heart begins beating; ribs, muscles and digestive tract form. 5-8 weeks: Arms and legs develop, then fingers and toes. Placenta and umbilical cord function; liver produces blood cells; embryo responds to touch. Heart develops separate chambers. 9-12 weeks: Fetal period unitl birth Genitals form and release sex hormones; fingernails, toenails, and taste buds develop. Heartbeat audible with stethoscope. Second trimester 13-24 weeks: Mother feels movement; fetus kicks, turns, hiccups, sucks thumb, breathes amniotic fluid, responds to sounds, especially music and familiar voices; vernix and lanugo develop on skin for protection. Third trimester 25-38 weeks: Lungs develop fully; over two-thirds of birth weight is gained; brain development accelerates; sleep-wake cycle resembles newborn's.

Answer 8

Ball of about 100 cells formed by 1 week after conception. The blastocyst is divided into two layers. The outer layer of cells, called the trophoblast, will form the structures that provide protection and nourishment. The inner layer of cells, the embryonic disk, will become the embryo of the new organism. 50% don't implant successfully.

Answer 9

Fluid-filled membrane that surrounds and protects the developing organism.

Answer 10

It also acts as a gatekeeper, protecting the developing organism from bacteria and wastes in the mother’s blood, and it produces hormones that maintain the blood in the uterine lining and cause the mother’s breasts to produce milk.

Answer 11

Implantation is the outcome of the germinal period if all goes well. However, it is estimated that over half of blastocysts never implant successfully, usually due to chromosomal problems that have caused cell division to slow down or stop. If implantation fails, the blastocyst will be eliminated from the woman’s body along with the bloody uterine lining during her next menstrual period.

Answer 12

In prenatal development, elapsed time since conception.

Answer 13

The outer layer, the ectoderm, will become the skin, hair, nails, sensory organs and nervous system. The middle layer, the mesoderm, will become the muscles, bones, reproductive system and circulatory system. The inner layer, the endoderm, will become the digestive system and the respiratory system. The nervous system develops first and fastest. Once formed, the neural tube begins producing neurons in immense quantities, over 250,000 per minute.

Answer 14

A full-term fetus is defined as 38 weeks or more gestation. Babies born before 22 weeks rarely survive, even with the most advanced technological assistance. More than 60% of preterm births occur in Africa and south Asia. In low-income countries, 50% of babies born at 32 weeks survive, but in high-income countries, almost all of them survive. The lungs are the last major organ to become viable, and even a baby born in the seventh or early eighth month may need a respirator to breathe properly. During the last trimester the typical fetus gains over 2200 grams, and this additional weight helps it sustain life. Babies born weighing less than 2500 grams are at risk for a wide range of problems. Women should typically gain 11–16 kilograms during pregnancy, and women who gain less than 9 kilograms are at risk of having babies who are preterm and low birth weight.

Answer 15

Benefits to the mother include lower likelihood of back pain, less swelling of the joints and better sleep. Babies whose mothers received prenatal massage score higher on scales of their physical and social functioning in the early weeks of life.

Answer 16

Have a medical examination to ensure there are no diseases that may affect prenatal development. If not fully vaccinated, follow medical advice regarding vaccinations for diseases, such as rubella, that can damage prenatal development, or COVID-19, that can potentially cause complications. Avoid tobacco, alcohol and other drugs, which may make it more difficult to become pregnant and are damaging to prenatal development.

Answer 17

Diet. Maintain a balanced diet, including protein, grains, fruit and vegetables. Avoid excessive fats, sugars and caffeine, and obtain sufficient iron and iodine. Gain 11–16 kilograms in total; avoid dieting as well as excessive weight gain. Women should also drink more fluids during pregnancy than they normally do, as the fetus needs fluids for healthy development and a pregnant woman’s body also requires more. Exercise. Engage in mild to moderate exercise regularly, including aerobic exercise. Aerobic exercise, such as walking, jogging or swimming, is related to decreased back pain, lower risk of gestational diabetes, better sleep and more energy. However, it is important to avoid strenuous exercise and high-risk sports, such as long-distance running, contact sports, downhill skiing, water skiing and horse riding. Teratogens. Avoid tobacco, alcohol and other drugs. Avoid exposure to X-rays, hazardous chemicals and infectious diseases.

Answer 18

Behaviours, environments and bodily conditions that could be harmful to the developing organism. The embryonic period, especially, is a critical period for prenatal development. Malnutrition most common worldwide. Alcohol and tobacco in developed countries. Infectious disease also in developing countries.

Answer 19

Organs such as the nervous system develop from the second week. Embryonic most critical. The heart is formed between weeks 3.5 and 6.5. Arms and legs between 4.5 and 7. Eyes from 4.5. Teeth before 7 and 9. External genitalia from 7. Ears from 4.5 and between 9 and 12.

Answer 20

In the 1980s, China had the highest incidence in the world of two serious prenatal disorders: anencephaly, in which parts of the brain are missing or malformed; and spina bifida, which is an extreme distortion in the shape of the spinal column. It was discovered that in both of these disorders the main cause is a deficiency of folic acid.

Answer 21

In 2009, the Australia New Zealand Food Standards Code legislated folic acid and iodine must be added to bread in Australia. Neural tube defects fell 14%, and among Indigenous mothers the drop was 74%. Iodine levels increased 52%. Iron-rich foods such as beef, duck, potatoes (including skin), spinach and dried fruits are important for building the blood supply of mother and fetus. The WHO estimates that nearly one-half of women worldwide are deficient in iron, placing them at risk for having preterm and low-birth-weight babies. Iodine is also crucial because low-iodine intake during pregnancy increases the risks of miscarriage, stillbirth and abnormalities in fetal brain development. In most developed countries salt has been iodised since the 1920s.

Answer 22

In sub-Saharan Africa, malaria infection in pregnancy accounts for 20% of fetal deaths. Malaria inflections during the second trimester are more likely to affect the growth of the fetus, which can result in low birth weight, stillbirth and risk of infant mortality.

Answer 23

There is evidence that mothers are at increased risk for preterm delivery, caesarean delivery, a serious condition called preeclampsia and haemorrhaging after birth. Newborns were also at higher risk of distress during labour and being admitted to intensive care, and had lower birth weights. Current medical research indicates that vaccines are safe for pregnant women and had no effect on delivery or newborn complications.

Answer 24

In developed countries, the teratogen that causes the most widespread damage to prenatal development is alcohol. Analysis of the Growing Up in New Zealand study found that 22.5% of pregnant women had some level of alcohol in the first trimester and 13.4% reported drinking after that. In 2013, 53% of pregnant Australian women abstained from drinking; many who drank did so before they knew they were pregnant, but 26% continued to consume alcohol when they knew they were pregnant.

Answer 25

Includes facial deformities, heart problems, misshapen limbs and a variety of cognitive problems such as intellectual disability and attention and memory deficits. In Australia, the incidence of FASD is estimated to be as much as 39 times higher for Indigenous children, but this incidence is still far lower than the rates seen among indigenous populations from other countries.

Answer 26

Women who smoke during pregnancy are at higher risk for miscarriage and premature birth, and smoking is the leading cause of low birth weight in developed countries. Maternal smoking raises the risks of health problems in infants, such as impaired heart functioning, difficulty breathing and even death. In Australia and New Zealand, respectively 10% and 13% of pregnant women reported smoking during pregnancy. Prenatal exposure to smoking predicts problems in childhood and adolescence, including poorer language skills, problems with attention and memory, and behaviour problems. Second-hand smoke from others’ smoking leads to higher risks of low birth weight and childhood cancer.

Answer 27

Maternal use of drugs such as cocaine, heroin and marijuana causes physical, cognitive and behavioural problems in infants. Certain prescription drugs can also cause harm. Even non-prescription drugs such as cold medicines can be damaging to prenatal development. Pregnant women are advised to avoid work that involves exposure to teratogens such as X-rays, hazardous chemicals or infectious diseases. Toxins in water, food or air.