Ch.29 Development and Inheritance study guide

Define differentiation

Creation of different cell types during development

- Occurs through selective changes in genetic activity

• Some genes are turned off, others are turned on

Define inheritance.

Transfer of genetically determined characteristics from generation to generation

Define fertilization.

joining of sperm and egg (gametes)

-involves the fusion of two haploid (n) gametes, each containing 23 chromosomes.

What enzyme is released from the acrosome that is used to penetrate the corona radiata?

hyaluronidase

After sperm binds to sperm receptors in the zona pellucida, two enzymes are released. State their names and their collective function

hyaluronidase -- breaks down bonds between adjacent follicle cells

acrosin -- protein digesting enzyme

In general, what is oocyte activation?

a series of changes in the metabolic activity of the oocyte

-leads to increased permeability of the oocyte membrane to sodium ions; the entry of sodium ions causes the membrane to depolarize. This depolarization in turn causes the release of calcium ions from the smooth endoplasmic reticulum into the oocyte cytoplasm.

What is polyspermy? What process is used to block polyspermy?

fertilization by more than one sperm

-cortical reaction

What is amphimixis?

The combining of the male and female chromosomes

Define gestation.

Gestation is the period of prenatal development. It consists of three trimesters.

What are two general processes that occur in the pre-embryonic period of the first trimester?

What are two general processes that occur in the embryonic period of the first trimester

cleavage and implantation

placentation and embryogenesis

Define placenta

complex organ that permits exchange between maternal and embryonic blood.

Define cleavage.

a sequence of cell divisions that begins immediately after fertilization.

-During cleavage, the zygote becomes a pre-embryo, which develops into a multicellular complex known as a blastocyst. Cleavage ends when the blastocyst first contacts the uterine wall.

What is a morula?

a solid ball of cells resembling a mulberry (after three days of cleavage)

What is a blastocyst and blastocoele?

blastocyst -- a hollow ball of cells with an inner cavity blastocoele, and outer cells, trophoblasts.

blastocoele -- inner cavity of blastocyst

What is the trophoblast?

Outer layer of cells of blastocyst

• Provides nutrients to developing embryo

What does the inner cell mass of a blastocyte become?

an embryo

Define ectopic pregnancy.

fertilized egg implants outside the uterus

What hormone does the trophoblast and chorion produce?

human chorionic gonadotropin (hCG)

What hormones do the corpus luteum and placenta produce?

progesterone and estrogen

What occurs during gastrulation? Name the three germ layers.

cell migration

-Ectoderm• Mesoderm• Endoderm

What are the two main functions of the yolk sac?

primary nutrient source

site for blood cell formation

What does the amnion produce?

amniotic fluid

What organ does the chorion develop into?

placenta

What is the function of the umbilical cord?

supplies the fetus with life-sustaining substances and removes wastes.

What vessels carry blood from the fetus to the placenta?

umbilical arteries

What is the function of the chorionic villi?

provide the surface area for active and passive exchanges of gases, nutrients, and wastes between the fetal and maternal bloodstreams.

Which trimester is the most critical for fetal development?

first trimester

During which trimester is the most weight gained by the fetus?

third trimester

Which pregnancy hormone is detected in the urine when performing a home pregnancy test? Please know the name and abbreviation of the hormone

human chorionic gonadotropin (hCG)

What is the function of human chorionic gonadotropin?

it maintains the integrity of the corpus luteum and promotes the continued secretion of progesterone. As a result, the endometrial lining remains perfectly functional, and menstruation does not normally occur.

What is the function of human placental lactogen? Please know the name and abbreviation of the hormone.

hPL helps prepare the mammary glands for milk production

-Ensures that glucose and protein are available for fetus

Which hormone produced by the placenta and corpus luteum suppresses the release of oxytocin by the hypothalamus and delays the onset of labor contractions

relaxin

Define parturition and labor.

childbirth

uterine contractions to push out baby

What are Braxton Hicks contractions

Late in pregnancy, some women experience occasional spasms in the uterine musculature, but these contractions are not regular or persistent (false labor)

List the three stages of labor in the order they occur

the dilation stage, the expulsion stage, and the placental stage

What membrane ruptures when a birthing person's water breaks

the amniochorionic membrane

What does the Apgar score indicate?

clinicians assess the newborn's health in five areas: heart rate, breathing, skin color, muscle tone, and reflex response. This assessment is called an Apgar score.

What is a breech birth?

In 3-4 percent of deliveries, the legs or buttocks of the fetus enter the vaginal canal first.

What is the difference between dizygotic and monozygotic twins?

dizygotic: fraternal twins

monozygotic: identical twins

When does the neonatal period occur?

from birth to 1 month of age.

List two proteins contained in colostrum. What are their functions?

mucins which inhibit the replication of rotaviruses

-- antibodies which help infants ward off infections

What enzyme is found in breast milk? What properties does it have

lysozyme- has antibiotic properties

Which hormone stimulates the milk ejection reflex

oxytocin

When does adolescence begin?

puberty

In general, why are boys usually taller than girls?

Girls generally do not grow as tall as boys because estrogens cause more rapid epiphyseal cartilage closure than does testosterone, and the period of skeletal growth ends at an earlier age in girls than in boys.

Why do premenopausal women have a lower incidence of arterial plaque formation?

Estrogens decrease plasma cholesterol levels and slow the formation of plaque. As a result, premenopausal women have a lower risk of atherosclerosis ("hardening of the arteries") than do adult men.

Define senescence

biological aging

Define gene, genotype, and phenotype.

gene: Functional segments of DNA; Each gene carries information needed to direct synthesis of a specific polypeptide

genotype: chromosome and their genes

phenotype -- anatomical and physiological characteristics

What is the difference between homologous chromosomes and sex chromosomes

HC are the two members of each of the 22 pairs

SC are the 23rd pair of chromosomes that determine if female or male

What is a karyotype?

entire set of chromosomes

Define locus and alleles

locus: Gene's position on a chromosome

alleles: Various forms of a given gene

When referring to gene traits, what is the difference between homozygous and heterozygous

homozy -- the same allele of a particular gene

heterozy -- two different alleles for the same gene

What is the difference between simple inheritance and polygenic inheritance?

Phenotype determined by interactions between single pair of alleles

phenotypic traits are determined by interactions among several genes.

What are the differences between strict dominance, co-dominance, and incomplete dominance?

strict dominance: Dominant allele is always expressed in phenotype• Recessive allele will be expressed only if same allele is present on both chromosomes

codominance: Heterozygous individual exhibits both phenotypes

incomplete dominance: Heterozygous alleles produce intermediate phenotype

What are Punnett squares used for?

Simple box diagram used to predict characteristics of offspring

What sex chromosome alleles do males have? What sex chromosome alleles do females have?

male: XY

female: XX

What are X-linked genes

Genes that are found on the X chromosome but not on the Y chromosome are called X linked.

Why are men more likely to be affected by recessive X-linked traits?

bc men only have one X chromosome

Listthree conditions that occur with recessive X-linked traits.

red-green color blindness

hemophilia

duchenne muscular dystrophy

What is the result of genetic recombination?

greatly increases the genetic variation among gametes, and thus among the genotypes formed when those gametes combine in fertilization.

Why do you think that only 0.5% of newborns have chromosomal abnormalities when ~10 percent of zygotes have chromosomal abnormalities

few individuals with chromosomal abnormalities survive to full term

What of clinical significance can the analysis of amniotic fluid detect?

can detect genetic disorders like Down syndrome, sickle cell disease, and neural tube defects

What is a translocation defect?

In a translocation defect, an exchange occurs between different (nonhomologous) chromosome pairs.

-For example, a piece of chromosome 8 may become attached to chromosome 14.

What genetic abnormality is the cause of Down's syndrome?

trisomy 21

What direct correlation has been observed that increases the risk of having a baby with Down's syndrome?

advancing maternal age and the risk of having a child with trisomy 21.

Define epigenetics.

study of how a person's environment and behaviors can affect how their genes work, without changing the DNA sequence.• Acts by activating or inactivating specific genes

What are spontaneous mutations

Result from random errors in DNA replication

What are teratogens?

Factors that result in abnormal development

-alcohol, drugs, etc.

What is gene therapy?

Gene therapy involves inserting corrective genes made in a laboratory into a patient's cells to treat disorders or diseases caused by genetic defects.