Development and Inheritance

What is the first stage of development following fertilization?

The zygote, which is diploid and contains 46 chromosomes.

What is the typical duration of pregnancy measured from the last menstrual period?

Around 40 weeks.

What are the two main types of cells that combine during fertilization?

A sperm cell from the father and a secondary oocyte from the mother.

What are the stages of early development after fertilization?

Cleavage, blastocyst formation, and implantation.

What term describes the rapid mitotic divisions of the zygote?

Cleavage.

What structure forms when the blastocyst reaches about 100 cells?

The blastocyst, which has an inner cell mass and an outer layer called the trophoblast.

What critical process occurs when the blastocyst implants itself into the endometrium?

Implantation.

What hormone does the trophoblast secrete after successful implantation?

Human chorionic gonadotropin (hCG).

What role does hCG play in early pregnancy?

It signals the ovaries to maintain the corpus luteum, crucial for hormone production.

What are the three germ layers formed during gastrulation?

Ectoderm, mesoderm, and endoderm.

What does the ectoderm develop into?

The nervous system and skin.

During which weeks does organogenesis occur?

Weeks four to eight.

What is the fetal stage and when does it begin?

A period of rapid growth that begins at week nine of prenatal development.

What is the purpose of the ductus venosus in fetal circulation?

To bypass the fetal liver, directing most blood to the inferior vena cava.

What marks the transition from the embryonic stage to the fetal stage?

The end of organogenesis, around week nine.

What is the recovery phase following delivery called?

Postpartum period.

What is lochia?

Controlled bleeding that occurs as the endometrium shrinks post-delivery.

What is the primary adjustment for a neonate immediately after birth?

Respiration.

Which hormones are involved in the process of lactation?

Prolactin and oxytocin.

What is the purpose of breast milk during the neonatal period?

To provide essential nutrients and antibodies for development.

What genetic structures do humans possess and how many?

Humans have 46 chromosomes, with 23 inherited from each parent.

What is a karyotype?

The arrangement of chromosomes in pairs.

What is the difference between homologous chromosomes?

They carry the same types of genes but may have different alleles.

What is an allele?

A variant form of a gene.

What is the phenotype?

The physical expression of an individual's genotype.

What are multifactorial traits?

Traits influenced by multiple genes and environmental factors.

What is the Punnett square used for?

To visualize simple inheritance patterns.

What is codominance?

A pattern where both alleles are equally expressed in the phenotype.

What is an example of incomplete dominance?

When crossing red and white flowers produces pink flowers.

What are lethal genes?

Alleles that can lead to a significantly shortened lifespan.

What is an example of a dominant lethal gene?

Huntington's disease.

What does multifactorial inheritance refer to?

Phenotypes influenced by multiple genes and environmental factors.

What is aneuploidy?

A chromosomal disorder arising from nondisjunction during meiosis.

What is trisomy 21 commonly known as?

Down syndrome.

What is one method for diagnosing chromosomal abnormalities prenatally?

Chorionic villus sampling.

What defines the human lifespan, according to the lecture?

Theoretical maximum is around 120 years, influenced by health factors.

What are the leading causes of death in the U.S.?

Heart disease, cancer, and medical errors.

What role does estrogen play during pregnancy?

Promotes the growth and maturation of fetal tissues.

What role does progesterone have in pregnancy?

Inhibits uterine contractions to maintain a conducive environment for the fetus.

What marks the phase of development where the embryo features increasingly align with newborn characteristics?

The fetal stage.

What structure becomes the ligamentum venosum after birth?

The ductus venosus.

What adjustments must neonates make in regards to their circulatory system after birth?

Closure of the ductus venosus, ductus arteriosus, and foramen ovale.

What is the importance of vaginal delivery for the newborn?

It promotes healthy microbial colonization of the gut.

What is the purpose of the umbilical cord after birth?

To provide nutrients and oxygen to the fetus during gestation.

What are the two types of traits characterized in genetics?

Dominant and recessive traits.

What can heterozygotes be carriers of in terms of alleles?

Recessive alleles without exhibiting harmful effects.

What does the study of genetics help with in terms of offspring?

Deducing probable outcomes for traits and recognizing inherited health issues.

What is the primary function of relaxin during early pregnancy?

To support relaxation of uterine muscles and pelvic ligaments.

How does the Y chromosome influence male development?

It triggers the development of male genitalia.

What significant change occurs to fetal circulation at birth?

Blood begins to flow to the lungs for oxygenation.

What is the role of the placenta during pregnancy?

To exchange nutrients and waste between the mother and the fetus.

What happens to the corpus luteum after implantation and what hormone is involved?

It is maintained by hCG to continue hormone production.

How do dominant alleles affect phenotypes in a heterozygous situation?

They can mask recessive alleles.

What is the primary characteristic of multifactorial traits?

They are influenced by both multiple genes and environmental factors.