APII Final Exam

Development, Pregnancy, Heredity

Describe where fertilization occurs & fetal development

Fertilization, the joining of sperm and egg, typically occurs in the fallopian tubes. After fertilization, the resulting single-cell embryo, called a zygote, begins to divide and develop as it travels down the fallopian tube towards the uterus. In the uterus, the developing embryo, now a blastocyst, implants into the uterine lining, marking the beginning of fetal development

Describe zygote formation

• the haploid nucleus in the head of the sperm becomes the male pronucleus

• The haploid nucleus of the fertilized ovum becomes the female pronucleus

• When the two merge, the diploid zygote is formed

List & describe the various periods of development

Prenatal Development: This period spans from conception to birth, encompassing the germinal, embryonic, and fetal stages. It's a time of rapid growth and development, with the fetus undergoing significant physical changes

List the primary hormones controlling lactation.

Human chorionic somatomammotropin (hCS), also known as human placental lactogen (hPL), is thought to help prepare the mammary glands for lactation, help maternal growth, and regulate metabolism in mother and fetus

allele

• the genotype is the actual genetic makeup relating to a trait

• An allele that dominates or masks the presence of another allele is a dominant allele (represented by an upper case letter)

• The allele whose presence is completely masked is the recessive allele (represented by a lower case letter)

• Phenotype is the physical expression of the genotype

Genotype

A genotype is an organism's genetic makeup, specifically the combination of alleles (versions of a gene) it possesses for a particular trait or gene. It represents the inherited genetic code that influences, but doesn't directly determine, an individual's observable characteristics, or phenotype

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

List & describe the major types of inheritance

The major types of inheritance are Mendelian inheritance, which includes autosomal dominant, autosomal recessive, and X-linked inheritance. These patterns describe how traits are passed down from one generation to the next based on the location of genes on chromosomes. Other types of inheritance include multifactorial inheritance, where multiple genes and environmental factors contribute to a trait, and mitochondrial inheritance, which involves genes passed down through the mitochondria.

Describe the inheritance of sickle cell anemia.

• Incomplete dominance

• Sickle cell anemia is inherited in an autosomal recessive pattern. This means that an individual must inherit two copies of the altered gene, one from each parent, to develop the condition. If an individual inherits only one copy of the altered gene, they are considered a "carrier" and may not show symptoms but can pass the gene on to their children

List & describe the 2 sex chromosomes

Female and Male genotype and possible gametes

• X and Y chromosome are not homologous

  • X has around 900 genes

  • Y had around 55 genes

• X-linked recessive diseases predominant in males (passed from mother to son)

  • Y chromosome lacks the gene that could mask it

  • Hemophilia, color blindness, baldness

• Y-linked recessive diseases pass from father to son

Sex linked disorders

• Errors in meiosis lead to too many or too few chromosomes

• Sex chromosomes:

• Turner’s Syndrome (XO) - short, infertile, hearing loss, cardiovascular problems

• Klinefelter’s Syndrome (XXY) - mixed secondary characteristics, low sperm count

• Autosomes:

  • Trisomy 21 - extra copy of chromosome 21, down syndrome, distinct physical characteristics, low resistance to infection, mental retardation