Biology Chapter: Reproduction and Inheritance

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Questions and Answers

What role does oxytocin play in the reproductive system?

  • It stimulates contraction of the uterus. (correct)
  • It stimulates the production of progesterone.
  • It contributes to the degeneration of the corpus luteum.
  • It decreases the levels of estradiol.

Which extracellular ion is pumped out by the Na+/K+ ATPase?

  • Sodium (Na+) (correct)
  • Calcium (Ca2+)
  • Magnesium (Mg2+)
  • Chloride (Cl-)

During the resting potential of a neuron, which ion channels are primarily closed?

  • Chloride channels
  • Calcium channels
  • Sodium channels (correct)
  • Potassium channels

What happens during the falling phase of an action potential?

<p>Potassium channels are opened, allowing potassium to flow out. (D)</p> Signup and view all the answers

What indicates a higher affinity for potassium in the Na+/K+ ATPase cycle?

<p>Phosphorylation by ATP. (B)</p> Signup and view all the answers

Which of the following is a type of chemical signal used in cell-cell communication?

<p>Neurotransmitters. (A)</p> Signup and view all the answers

During what phase of action potential generation do voltage-gated sodium channels open?

<p>Rising phase. (B)</p> Signup and view all the answers

What occurs immediately after the threshold is crossed during action potential?

<p>Sodium channels begin to open. (C)</p> Signup and view all the answers

What structure is formed from the Wolffian duct in males?

<p>Vas deferens (A)</p> Signup and view all the answers

Which hormone is primarily secreted by Leydig cells?

<p>Testosterone (D)</p> Signup and view all the answers

What triggers contraction of the uterus during labor?

<p>Oxytocin and prostaglandins. (D)</p> Signup and view all the answers

What is the effect of the Na+/K+ ATPase on cellular ion balance?

<p>It creates an electrochemical gradient across the membrane. (A)</p> Signup and view all the answers

What is the main role of FSH in female reproduction?

<p>Stimulate follicle development (C)</p> Signup and view all the answers

During which stage does sex differentiation of internal genitalia occur?

<p>Gastrulation (A)</p> Signup and view all the answers

What structure regresses in males during development?

<p>Müllerian duct (C)</p> Signup and view all the answers

What process begins the formation of a three-layered embryo?

<p>Gastrulation (B)</p> Signup and view all the answers

Which gene is responsible for initiating testis formation?

<p>SRY gene (D)</p> Signup and view all the answers

Which structure develops into the corpus luteum post-ovulation?

<p>Follicle (D)</p> Signup and view all the answers

Which hormone is responsible for thickening the endometrium?

<p>Progesterone (C)</p> Signup and view all the answers

At what point does oogenesis typically halt?

<p>At birth (A)</p> Signup and view all the answers

What is the result of sperm maturation in males?

<p>Development of secondary spermatocytes (B)</p> Signup and view all the answers

What does the genital tubercle develop into in females?

<p>Clitoris (C)</p> Signup and view all the answers

Which hormone is responsible for stimulating ovulation?

<p>LH (A)</p> Signup and view all the answers

What is the outcome of no fertilization in oogenesis?

<p>Development of a polar body (B)</p> Signup and view all the answers

What is the primary role of ligands in cell signaling?

<p>They bind to receptors to initiate a signal. (B)</p> Signup and view all the answers

Which type of hormone is characterized as water-soluble?

<p>Polypeptide hormones (C)</p> Signup and view all the answers

What is one method through which steroid hormones typically exert their effects?

<p>By directly entering the cell and binding to nuclear receptors. (B)</p> Signup and view all the answers

What is the first stage of cell signaling?

<p>Reception (A)</p> Signup and view all the answers

Which of the following describes local signaling?

<p>It occurs through direct contact between cells. (B)</p> Signup and view all the answers

What characterizes steroid hormones as opposed to polypeptide hormones?

<p>They are lipid-soluble and can enter cells easily. (A)</p> Signup and view all the answers

What occurs during the transduction stage of cell signaling?

<p>The signal is converted into a cellular response. (B)</p> Signup and view all the answers

Which of the following options is NOT a method for local signaling?

<p>Long-distance hormonal signaling. (B)</p> Signup and view all the answers

How do signaling molecules typically lead to a response in target cells?

<p>They initiate a series of biochemical reactions inside the cell. (D)</p> Signup and view all the answers

Which component does NOT play a role in cell signaling?

<p>Hemoglobin (A)</p> Signup and view all the answers

What is one way through which local signaling occurs between animal cells?

<p>By direct contact through cell junctions (C)</p> Signup and view all the answers

Which class of hormone is characterized as lipid-soluble and able to diffuse through the cell membrane?

<p>Steroids (D)</p> Signup and view all the answers

During the reception stage of cell signaling, what occurs when a signaling molecule binds to a receptor?

<p>The receptor undergoes a conformational change (B)</p> Signup and view all the answers

What is NOT a typical method of signaling used for long-distance communication between cells?

<p>Paracrine signaling between nearby cells (B)</p> Signup and view all the answers

Which statement correctly describes polypeptide hormones?

<p>They bind to receptors on the surface of target cells. (A)</p> Signup and view all the answers

What is a characteristic function of ligands in cell signaling?

<p>To bind specifically to receptors and initiate a signaling cascade (A)</p> Signup and view all the answers

Which process is NOT involved in maintaining the membrane potential during the action potential generation?

<p>Phosphorylation by ATP (A)</p> Signup and view all the answers

Which stage of cell signaling involves the actual changes occurring within the target cell after receptor activation?

<p>Response (C)</p> Signup and view all the answers

What occurs during the undershoot phase of an action potential?

<p>Sodium channels are inactivated, and potassium channels are still open (D)</p> Signup and view all the answers

What initiates uterine contractions during labor?

<p>Secretion of oxytocin (B)</p> Signup and view all the answers

What distinguishes steroid hormones from other hormones in terms of their action?

<p>They can directly influence gene expression within the target cell. (C)</p> Signup and view all the answers

What is the role of receptor proteins in cell signaling?

<p>To detect signaling molecules and initiate cellular responses (A)</p> Signup and view all the answers

Which of the following correctly describes the action of the Na+/K+ ATPase?

<p>It helps maintain the electrochemical gradient through active transport (D)</p> Signup and view all the answers

What does the term 'transduction' refer to in cell signaling?

<p>The pathway through which a signal is amplified inside the cell (A)</p> Signup and view all the answers

What type of signaling involves the use of neurotransmitters and hormones?

<p>Chemical signaling (A)</p> Signup and view all the answers

Which factor primarily influences the shape change and ion affinity in the Na+/K+ ATPase cycle?

<p>Presence of ATP molecule (B)</p> Signup and view all the answers

What describes the role of oxytocin in relation to the trophoblast?

<p>Promoting contraction of uterine muscles during labor (D)</p> Signup and view all the answers

Which of the following is primarily closed during resting potential in neurons?

<p>Voltage-gated sodium channels (A)</p> Signup and view all the answers

What effect does the corpus luteum have if fertilization does not occur?

<p>It degenerates, leading to reduced hormone levels (C)</p> Signup and view all the answers

What is the primary electrical consequence of Na+ ions flowing into a neuron?

<p>Depolarization of the membrane potential (A)</p> Signup and view all the answers

What is the outcome of the regression of the Wolffian duct in females?

<p>Formation of the ovaries (C)</p> Signup and view all the answers

What triggers testosterone production in males?

<p>Individuals serving the Leydig cells (D)</p> Signup and view all the answers

What impact does the SRY gene have on sex differentiation?

<p>Promotes Leydig cell activity (C)</p> Signup and view all the answers

During spermatogenesis, what is the primary role of the primary spermatocyte?

<p>Undergoes meiosis to form secondary spermatocytes (B)</p> Signup and view all the answers

What role does FSH play in female reproductive physiology?

<p>Stimulates follicle development (B)</p> Signup and view all the answers

What is the result of excessive AMH secretion in males?

<p>Regression of the Mullerian duct (A)</p> Signup and view all the answers

At what point does oogenesis pause until fertilization?

<p>At the primary oocyte stage (A)</p> Signup and view all the answers

What structure does the genital tubercle develop into in males?

<p>Glans penis (C)</p> Signup and view all the answers

What hormone is secreted by the corpus luteum to maintain the endometrium?

<p>Progesterone (D)</p> Signup and view all the answers

What initiates the thickening of the endometrium during the menstrual cycle?

<p>Estrogen stimulation (D)</p> Signup and view all the answers

What happens to the Mullerian ducts in the presence of the SRY gene?

<p>They undergo regression (A)</p> Signup and view all the answers

During what phase is testosterone produced in the male reproductive system?

<p>During puberty (A)</p> Signup and view all the answers

Which structure is responsible for spermatogenesis?

<p>Seminiferous tubules (D)</p> Signup and view all the answers

What triggers the onset of labor in pregnancy?

<p>Surge of oxytocin (C)</p> Signup and view all the answers

Flashcards

Local signaling

Signaling between cells that are in close proximity.

Direct contact signaling

Direct cell-to-cell communication via cell junctions or membrane molecules.

Cell-cell communication

Signaling between animal cells where proteins serve as messengers.

Ligand-receptor binding

A signaling molecule (ligand) binds to a receptor protein.

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Local regulators

Signaling molecules that act over short distances.

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Hormones

Signaling molecules used for long-distance communication.

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Polypeptide hormones

Water-soluble hormones often consisting of chains of amino acids.

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Steroid hormones

Lipid-soluble hormones derived from cholesterol.

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Cell-surface receptors

Receptors found on the surface of target cells that bind to water-soluble hormones.

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Cell signaling stages

The three main steps in cell signaling: reception, transduction, and response.

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Menstruation (low level)

Menstruation occurs when no fertilization occurs. The corpus luteum degenerates, reducing estrogen and progesterone levels.

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Trophoblast

Part of the placenta.

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Oxytocin and Prostaglandins

Hormones that stimulate uterine contractions.

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Extracellular fluid

The fluid outside cells.

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Sodium (Na+) binding

A protein changes shape when sodium binds to it. This changes the protein's sodium affinity.

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Phosphorylation (ATP)

ATP adds a phosphate group to a protein, changing its shape and function.

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Protein shape change

A protein's shape drastically changes when a chemical or physical interaction affects it. This influences the interaction with other molecules.

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Potassium (K+) affinity

Proteins (with a change in shape) have higher affinity for potassium.

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Action Potential (Rising Phase)

Sodium channels open, sodium flows inward, the membrane potential becomes more positive.

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Action Potential (Falling Phase)

Sodium channels become inactive, potassium channels open, leading to a rapid decrease in membrane potential.

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Sex Differentiation

The process where internal genitalia develop into male or female structures during embryonic development.

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Wolffian Duct

Embryonic duct that forms male reproductive structures if present.

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Millerian Duct

Embryonic duct that forms female reproductive structures if present.

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SRY protein

Sex-determining Region Y gene protein, triggers testis formation.

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Testis formation

Development of testes, leading to male reproductive organs.

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Gonadal Cortex

Structure in an embryo that develops into an ovary if a specific gene isn't present.

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Ovary development

The formation of the female reproductive organ.

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Leydig cells

Cells in the testes that produce testosterone.

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Spermatogenesis

Process of sperm cell production in males.

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Oogenesis

Process of egg cell production in females.

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FSH (Follicle-stimulating hormone)

Hormone that stimulates follicle development in the ovaries and sperm development in testes.

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LH (Luteinizing hormone)

Hormone that stimulates ovulation.

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Estrogen

A female sex hormone that thickens the lining of the uterus.

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Progesterone

A female sex hormone that maintains the thickened uterine lining.

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Genital Tubercle

Neutral embryonic structure that can form the clitoris or penis

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Cleavage

Rapid cell division after fertilization, resulting in a ball of cells with little gene expression and protein synthesis.

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Gastrulation

Process where the hollow ball of cells (blastula) folds inward, forming a three-layered embryo with ectoderm, mesoderm, and endoderm.

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What happens when fertilization doesn't occur?

The corpus luteum, a temporary structure in the ovary, degenerates. This causes a decrease in estrogen and progesterone levels, leading to menstruation.

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Role of Oxytocin and Prostaglandins

These hormones work together to stimulate contractions of the uterus during childbirth.

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Sodium-Potassium Pump

A protein pump that actively moves sodium ions out of the cell and potassium ions into the cell, maintaining the cell's membrane potential.

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Undershoot

The membrane potential briefly becomes even more negative than the resting potential due to the increased permeability of potassium ions.

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Physical vs. Chemical Signaling

Physical signals like light, pressure, and temperature can directly influence cells. Chemical signals, including neurotransmitters and hormones, use molecules to communicate between cells.

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Reception

The first stage in cell signaling, where a target cell detects a signaling molecule and binds it to a specific receptor.

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Transduction

The second stage in cell signaling, where the binding of a signaling molecule to a receptor triggers a series of molecular conversions inside the cell.

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Response

The final stage in cell signaling, where the cell produces a specific cellular response based on the received signal.

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Study Notes

Reproduction

  • New organisms originate from existing ones via sexual or asexual reproduction.
  • Sexual reproduction involves fertilization, producing unique cells through meiosis.
  • Asexual reproduction involves a single parent, creating clones through mitosis.
  • Human somatic cells contain 46 chromosomes (23 pairs of homologous chromosomes) displayed in a karyotype.
  • Sex chromosomes are X and Y; the rest are autosomes.

Meiosis and Fertilization

  • Meiosis transforms one diploid cell (2n) into four haploid cells (n), which are gametes.
  • Fertilization joins two haploid cells (gametes) to form a diploid cell (zygote).
  • Meiosis and fertilization alternate in sexual life cycles to maintain the chromosome number.

Sexual Life Cycle

  • Offspring inherit genes from parents through chromosomes.
  • Genes are the units of heredity, portions of DNA.
  • DNA is packaged into chromosomes.
  • A karyotype displays condensed chromosomes in an ordered fashion (largest to smallest).

Sex Differentiation

  • Embryos start as bipotential (can develop into either male or female).
  • Internal genitalia (testes and ovaries) develop based on genetic sex.
  • Hormones shape the development of external genitalia.

Spermatogenesis and Oogenesis

  • Spermatogenesis is the creation of sperm, a continuous process after puberty.
  • Oogenesis creates eggs and pauses until puberty.
  • FSH stimulates follicle development in ovaries and LH stimulates ovulation.
  • Progesterone is released by the corpus luteum to thicken the endometrium.

Endocrine Control of Childbirth

  • Estrogen and oxytocin (from mom/fetus) and Prostaglandins regulate uterine contractions during childbirth.
  • Positive feedback loop stimulates contractions. 

Cell Communication

  • Cell communication involves signal reception, transduction, and response.
  • Signals can be physical (light, pressure, temperature) or chemical (neurotransmitters, hormones).
  • Local regulators operate over short distances to regulate cell communication.

Types of Local Regulators

  • Endocrine signaling involves hormone release into the bloodstream for long-distance communication.
  • Paracrine signaling allows for signaling between nearby cells.
  • Autocrine signaling involves a cell signaling itself.
  • Synaptic signaling happens between neurons across a synapse.
  • Neuroendocrine signaling involves neurons that release hormones into the bloodstream.

Hormone Classes

  • Water-soluble hormones (peptides and amines) bind to cell surface receptors.
  • Lipid-soluble hormones (steroids) enter the cell and bind to intracellular receptors.

Membrane Receptors

  • Different types of cell-surface receptors exist for various functions.

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