exam 2 metacognition

What does the chromosome theory of inheritance state?

Genes are located on chromosomes; chromosome behavior during meiosis and fertilization explains inheritance.

What accounts for inheritance patterns?

The movement/segregation of chromosomes in meiosis and fertilization.

What is genetics? Who is the father of genetics?

Genetics = study of heredity and variation. Father of genetics = Gregor Mendel.

Why did Knight, Goss, and Mendel choose peas for experiments?

Peas are cheap, easy to grow, short generation time, many varieties, and can self- or cross-fertilize.

Instead of guessing, what did Mendel do first?

He analyzed inheritance patterns with controlled pea plant experiments.

Mendel deduced the fundamental principles of genetics, including that parents pass on what?

Discrete heritable factors (genes).

Mendel chose the garden pea for what 2 reasons?

1. Many identifiable traits. 2. Can self- or cross-pollinate.

What does self-pollination mean vs. cross-pollination?

Self = plant fertilizes itself. Cross = pollen from one plant to another.

What is a monohybrid cross?

A cross involving one trait (e.g., flower color).

Alternative forms of a gene at the same locus are called?

Alleles.

What 5 lessons did we learn from Mendel?

1. Genes exist. 2. Genes come in pairs (alleles). 3. Gametes get one allele (segregation). 4. Equal segregation (50/50). 5. Fertilization is random.

The gene may have different forms called what?

Alleles.

What is the principle of segregation?

Alleles separate during gamete formation; gametes carry only one allele.

What is random fertilization?

Any sperm can fertilize any egg, creating random allele combinations.

What is a homozygote? What letters represent a recessive homozygote?

Two identical alleles. Example: tt.

What is a heterozygote? What letters represent a heterozygote?

Two different alleles. Example: Tt.

What is the difference between a genotype and phenotype?

Genotype = genetic makeup. Phenotype = physical appearance.

What is the principle of independent assortment?

Alleles of different genes assort independently during gamete formation.

What is a carrier?

Individual with one recessive allele who does not show the trait but can pass it on.

What is an example of a dominant disorder? Is a dominant allele always more common?

Achondroplasia (dwarfism). No, dominant alleles are not always more common than recessive.

What is incomplete dominance?

Heterozygote shows intermediate phenotype (e.g., pink snapdragons).

What is hypercholesterolemia?

Incomplete dominance disorder with high cholesterol. Hh = mild disease, hh = severe disease.

What is an example of codominance/multiple alleles in humans?

ABO blood groups (A and B codominant).

What is pleiotropy? Example?

One gene affects multiple traits. Example: sickle-cell disease.

What is polygenic inheritance? Example?

Many genes affect one trait. Example: human skin color.

Recessive sex-linked traits are expressed more in who? Why?

Males, because they only have one X chromosome.

What is an example of a sex-linked blood disorder in humans?

Hemophilia.

What is hemophilia?

A sex-linked blood clotting disorder where blood fails to clot properly.

What is embryology?

The study of developmental changes before birth.

When is the embryonic period?

First 8 weeks of development.

What major events occur during the embryonic period?

Organs form from the 3 germ layers; basic body plan emerges.

When is the fetal period?

Weeks 9–38 of development.

What major events occur during the fetal period?

Organs grow in size and complexity.

What are the stages of the first week?

Zygote → 4-cell → Morula → Blastocyst.

What is the embryo called during implantation?

Blastocyst.

What is gastrulation?

Process where epiblast cells form 3 germ layers.

What are the three germ layers?

Ectoderm, Mesoderm, Endoderm.

What happens during neurulation?

Ectoderm forms brain and spinal cord via neural tube.

What forms from ectoderm?

Brain, spinal cord, epidermis, hair, nails, glands of skin.

What forms from mesoderm?

Muscles, bones, heart, blood vessels, kidneys, gonads, dermis.

What forms from endoderm?

Inner lining of digestive/respiratory tracts, organs, bladder.

What happens from week 5–8?

Limb buds form, embryo looks human, major organs in place.

What happens during the fetal period?

Rapid growth, differentiation, maturation.

What is the largest organ of the human body?

The skin.

How much of the total body mass is skin?

About 7% of body weight.

What are the functions of skin?

Protection, UV screening, vitamin D synthesis, insulation, prevents water loss, regulates temp, excretion, sensation.

What are the 4 cell types in the epidermis?

Keratinocytes (most abundant), Melanocytes (make melanin), Merkel cells (touch receptors), Langerhans cells (immune).

What are the layers of the epidermis?

Basale → Spinosum → Granulosum → Lucidum (thick skin) → Corneum.

What are epidermal ridges?

Fingerprints from dermal papillae.

What causes stretch marks (striae)?

Tearing of collagen fibers in dermis (pregnancy/obesity).

Is the hypodermis part of the skin?

No, but it anchors skin and insulates.

What do UV rays stimulate?

Vitamin D production.

Which layer has the most adipose tissue?

Hypodermis.

Which layer contains pigment?

Epidermis (melanin in melanocytes).

Which cell polices the body surface?

Langerhans cells.

Which cell is most abundant in epidermis?

Keratinocytes.

What is keratin?

Tough protein that protects skin.

What happens when Langerhans cells leave skin?

They migrate to lymph nodes and activate T-cells.

What are the 2 dermal plexuses?

Cutaneous plexus (deep) and subpapillary plexus (superficial).

What holds the epidermis and dermis together?

Undulating border/dermal papillae.

How is sebum made?

Holocrine secretion (whole cells break up).

What is true sweat?

99% water + salts/waste, acidic.

Difference between melanin, carotene, hemoglobin?

Melanin = pigment, Carotene = yellow-orange, Hemoglobin = red from blood.

What is hair made of?

Dead, keratinized cells.

What are the 3 layers of hair?

Medulla, Cortex, Cuticle.

What part of hair is visible?

Shaft.

What does the nail rest on?

Nail bed (epidermis).

What are the functions of bone?

Support, protection, movement, mineral storage, blood cell formation, energy storage.

What is the perichondrium? What does it act as?

Dense connective tissue around cartilage; resists outward expansion.

How many bones do we have?

206 in adult skeleton.

What is hyaline cartilage? Function?

Most abundant cartilage; provides support with flexibility.

What is elastic cartilage? Function?

Contains elastic fibers; tolerates repeated bending.

What is fibrocartilage? Function?

Contains thick collagen; resists compression and tension.

Difference between appositional and interstitial growth?

Appositional = growth from outside. Interstitial = growth from within.

What is it called when bones make contact?

Joint (articulation).

Difference between axial and appendicular skeleton?

Axial = central (skull, vertebrae, ribs). Appendicular = limbs/appendages.

Difference between compact and spongy bone?

Compact = dense outer layer. Spongy = inner trabecular network.

What is the epiphyseal plate?

Hyaline cartilage plate where bone grows in length.

Once long bone stops growing, what happens?

Plate becomes epiphyseal line.

What is the nutrient foramen?

Opening for blood vessels into medullary cavity.

What is an osteon?

Structural unit of compact bone, cylindrical pillar.

Each concentric ring is called?

Lamella.

What is an osteocyte?

Mature bone cell that maintains matrix.

What are the organic compounds of bone?

Cells, collagen, ground substance (35%).

What are the inorganic compounds of bone?

Hydroxyapatite (calcium phosphate) (65%).

What type of cartilage does bone replace in embryo? When?

Hyaline cartilage; around week 8 of development.

What is osteogenesis?

Process of bone formation (ossification).