Reproduction & Genetics Quiz

• The body's coordinated functions involve the endocrine, nervous, and reproductive systems.
• A stimulus produces a response.

Nervous System

• The nervous system includes the brain, spinal cord, and a complex network of nerves.
• It sends messages back and forth between the brain and the body.
• It is constantly alive with electricity and is the body's prime communication and coordination network.
• The nervous system is divided into two parts: the central and the peripheral nervous systems.

Neurons

• Neurons are the basic units of function and structure of the nervous system.
• They carry information through the nervous system through nerve impulses.

Types of Neurons:

• Sensory neurons receive initial stimuli from receptors and transmit nerve signals to the spinal cord.
• Interneurons "read" impulses and determine the response that should be generated.
• Motor neurons transmit impulses from the brain to the effector cells.

Reflex Reactions

• Reflex reactions happen without thinking and are involuntary.
• The central nervous system sends electrical signals to the muscles before the brain processes the message.
• Sensory neurons carry information to the spinal cord.
• Interneurons pass the impulse to motor neurons.
• Motor neurons carry impulses to the muscles.

Behavior

• Behavior is the way a person acts in response to a stimulus or situation, which can aid survival.
• A stimulus is a thing or event that evokes a specific functional reaction in an organ or tissue.

Stimuli

• External stimuli are changes in the environment around us, for example the heat of an oven.
• Internal stimuli are changes inside the body, for example the feeling of hunger.

Nervous Systems

• The autonomic nervous system consists of nerves that connect the central nervous system to visceral organs like the heart, stomach, and intestines and mediates unconscious activities.
• The somatic nervous system consists of nerves that go to the skin and muscles and is involved in conscious activities.

Egg Production

• All females are born with approximately two million egg cells in their lifetime.
• By the time the female reaches puberty, the egg cells will be down to about 400,000.
• Like sperm cells, egg cells also contain 23 chromosomes.
• During puberty, the increased production of hormones enables one immature egg to complete its development each month.
• A mature egg is called an ovum (ova).

Ovaries and Uterus

• Ovaries are where the egg is produced.
• The uterus id where the ovum goes if no sperm is present to fertilize the egg.

Endometrium, Progesterone, and Ovulation

• The endometrium is the inner lining of the uterus, which sheds during menstruation.
• Progesterone is a sex hormone that signals the body to prepare for fertilization.
• Ovulation involves the monthly release of an ovum from the ovary.

Follicles

• Follicles are clusters of cells that surround the immature egg.

PMS

• If you do get pregnant, your body will produce human chorionic gonadotropin (hCG), which is detected by pregnancy tests.
• If pregnancy does not occur, the corpus luteum shrinks and is resorbed, leading to decreased levels of estrogen and progesterone.
• The uterine lining is shed during the period.
• One may experience premenstrual syndrome (PMS).

Potential PMS Symptoms

• Bloating
• Breast swelling
• Mood swings
• Headache
• Weight gain
• Food cravings

Hormone Levels During Menstruation

• Progesterone: low
• Estrogen: low
• LSH (luteinizing hormone): low
• FH (follicle-stimulating hormone): low

Hormone Levels During the Luteal Phase

• Progesterone: high
• Estrogen: low
• LSH (luteinizing hormone)
• FH (follicle-stimulating hormone)
• The luteal phase starts after ovulation and ends on the first day of your period.

Hormone Levels During the Follicular Stage

• Progesterone: low
• Estrogen: high
• LSH: high
• FH: high

Hormone Levels During Ovulation

• Progesterone: high
• Estrogen: high
• LSH: high
• FH: high

Corpus Luteum

• The corpus luteum is the term for the yellow hormone-secreting body that secretes progesterone and estrogen, which causes the uterine lining.

Fallopian Tube

• The fallopian tube is the site of fertilization.
• Protein synthesis starts with the identification of DNA as genetic material.

Genetics

• Genetics is the branch of biology concerned with the study of heredity and variations.
• Variation refers to the differences between individuals within a species.

Identification of DNA as Genetic Material

• Information: DNA must contain the information necessary to make an entire organism.
• Transmission: It must be passed from parent to offspring.
• Replication: It must be copied.
• Variation: It must be capable of changes.

Nucleic Acid structure

• DNA and RNA are large macromolecules with several levels of complexity.
• Nucleotides form the repeating units, which are the basic building block of nucleic acids.
• Nucleotides are linked to form a strand.
• Two strands can interact to form a double helix.
• The double helix folds, bends, and interacts with proteins, resulting in 3-D structures in the form of chromosomes.

Chargaff's Rule

• In DNA, there is always equality in quantity between the bases A and T, and between the bases G and C.
• One example:
• One side: ATA TCA TGC GGG
• Other side: TAT AGT ACG CCC
• Second example:
• One side: AGT GAA CAT TA A
• Other side: T C A CTT GTA ATT

RNA

• RNA is single-stranded
• RNA is not found in chromosomes because it does not carry the genetic code
• RNA reads the DNA code and takes the information out of the nucleus.
• RNA's main job is to build proteins!

DNA

• DNA is double-stranded.
• DNA cannot leave the nucleus.

Messenger RNA

• It carries the complementary genetic code copied from DNA during transcription in the form of triplets of nucleotides called codons.

Ribosomal RNA

• Ribosomal RNA (rRNAs) combine with proteins and enzymes in the cytoplasm to form ribosomes, which act as the site of protein synthesis.

Transfer RNA

• Transfer RNA (tRNAs) is essential for translation.
• Their main function is the transfer of amino acids during protein synthesis.

Transcription

• Transcription is the transfer of genetic instructions in DNA to mRNA.
• RNA polymerase attaches to the promoter region of a gene on a strand of DNA.
• DNA strands separate, exposing nucleotides ready for copying.
• Messenger RNA (mRNA) pairs with a DNA template strand.
• Nucleotides are added until RNA polymerase reaches a termination sequence in the DNA and releases mRNA.
• mRNA moves out of the nucleus, through the nucleus pores, into the cytoplasm.

mRNA

• TAC TCG GGG CGC ATC CAA
• AUG AGC CCC GCG UAG GUU

Genetic Code

• T-A
• A-U
• C-G
• G-C
• A ribosome binds with a start codon in mRNA (AUG).
• Transfer RNA (tRNA) has a complementary anticodon that attaches to a corresponding mRNA codon, and it carries an amino acid.
• As the ribosome moves along the strand of mRNA, more amino acids are added to the growing chain.
• At the STOP codon, the ribosome releases the mRNA and an amino acid chain.
• The amino acid chain folds into a three-dimensional shape called a protein.

STOP Codons

• STOP codons: UAG, UAA, and UGA signal the end of the polypeptide chain during translation.
• For mRNA: AUG AGC CCC GCG UAG GUU
• For tRNA: UAC UCH GGG CGC AUC CAA

Genetic Mutation

• Mutation refers to changes in the chromosome of an organism that are inheritable and permanent, Mutations can happen spontaneously or can be caused by mutagens or mutagenic agents.

Types of Mutations

• Chromosome number
• Chromosome structure
• Nucleotide sequence

Chromosome Number

• A change in chromosomes may be euploidy (whole genome) or aneuploidy (change in the number of chromosomes)
• Klinefelter syndrome
• Turner syndrome
• Down syndrome

Aneuploidy

• Aneuploidy is often caused by a phenomenon called “nondisjunction,” which is the inability of the homologous sex chromosomes to segregate during meiosis

Down Syndrome

• Results from nondisjunction.
• Results in an embryo with three copies of chromosome 21 instead of the usual 2.
• Before or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate and is replicated in every cell of the body.
• It can happen to both males and females.

Klinefelter Syndrome

• It is when there is an extra X chromosome that is believed to be caused by a random error
• This error usually occurs during meiosis.
• Individuals with Klinefelter typically have small testes that produce a reduced amount of testosterone.

Turner Syndrome

• Where females typically have 2 X chromosomes but individuals with Turner syndrome only have 1
• When One copy of the X chromosome is missing or altered, reducing the functioning of the ovaries and causing the eggs to die prematurely and most ovarian tissue breaks down before birth.

Chromosome Structure

Deletion

• It is the Loss of a segment

Duplication

• When there is a Pair in excess

Inversion

• It is when a chromosome is reversed from end to end

Translocation

• The Transfer of a chromosome part to a nonhomologous chromosome.
• Example:
  • Normal: THE CAT RAN FAR
  • mutation: THE CAT CAT RAN FAR (duplication)
• Example:
  • Normal: THE CAT RAN FAR
  • mutation: THE RAT CAN FAR (inversion)
• Example:
  • Normal: ABCDEFG
  • mutation: ABCEFG (deletion)
• • Chrom 1: ABCD
• Chrom 2: EFGH
• after: ABCH
• After: EFGD (translocation)

Nucleotide Sequence

Point Mutation

• The deletion or insertion of one nucleotide pair

Frameshift Mutation

• The insertion or deletion of a number of nucleotides in the DNA sequence

Point mutation

• Nonsense mutation: this results in the formation of a STOP codon due to the substitution of a nitrogenous base
• Missense mutation: results when one nitrogenous base is replaced and the result is an altered codon that does not form into a stop codon
• Silent mutation - this happens, when one nitrogenous base is altered but the same amino acid is produced.

Sickle Cell Anemia

• it is a point mutation occurs in the beta-hemoglobin gene where It converts a GAG codon(6th codon) into GUG codon which encodes the amino acid rather than glutamic acid.
• It cannot carry oxygen as efficiently as normal round cells
• It is stiff and sticky making prone to clumping and blocking blood flow
• The life time of blood cells will be shortened from 120 days to 10-20 days

Evolution

• The idea of evolution evolved with Charles Darwin.
• Charles Darwin embarked from England on the beagle in Dec 1831 as the ship tried chart poorly known stretches of the South American coastline, which provided an opportunity for Darwin explore the continent and islands, including the Galápagos Islands.

Observations

• He notices that individuals in a population vary in their heritable characteristics, and that Organisms produce more offspring that the environment can support

Inferences

• individuals that are well suited to their environment tend to leave more offsprings than other individuals, so over time favorable traits accumulate the population

Natural Selection

• In The Origin of Species, Darwin proposed that evolution occurs by natural selection and because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations.
• Natural selection is a process in which individuals with certain heritable traits survive and reproduce at a higher rate than the others because of those traits.

Evidences of Evolution

• Embryology: descent from a common ancestor, they started the same but just gradually evolved with different traits
• Homology: traits present in two or more organisms that were inherited from the common ancesto, Similar body parts but different uses
• Vestigial structures: Structures of animals that are gradually disappearing and Lost their function through evolution; appendix
• Genetics: same ancestors, same genetic code
• Fossils: evolutionary changes that occurred in various groups of organisms
• Biogeography: The distribution of species on earth provides evidence that informs our understanding of both the evolution of life and the movement of continents

Test your knowledge of the female reproductive system, hormone functions, fertilization, and genetics. Questions cover egg cell count at puberty, hormone levels during the menstrual cycle, the role of tRNA in translation, and genetic disorders.