MCAT Biology 2

Nucleoid Region

DNA region in prokaryotes

Nucleolus

Makes ribosomes. Sits in nucleus, no membrane.

Peroxisomes

Collect and break down material

Rough ER

Accepts mRNA to make proteins

Smooth ER

Detox and make lipids

Golgi Apparatus

Modify/distribute proteins. Only in eukaryotes.

Centrioles

9 groups of microtubules, pull chromosomes aprt.

Lysosomes

Demo and recycling center. Made by golgi. Single membrane.

Plasmids

In prokaryotes. Carry DNA not necessary for survival.

Obligate Aerobe

Requires oxygen

Obligate Anaerobe

Dies in oxygen

Facultative Anaerobe

Toggle between aerobic/anaerobic

Aerotolerant Anaerobe

Does not use oxygen but can tolerate it well

Gram + is purple

Thick peptidoglycan/lipoteichoic acid cell wall

Gram - is pink-red

Thin peptidoglycan cell wall and an outer membrane

Prions

Infectious proteins. Trigger misfolding. Alpha-helical → beta-pleated sheets. Decreases solubility.

Viroid

Plant pathogens

Microfilaments

Actin

Microtubules

Tubulin

Intermediate Filaments

Keratin = vimentin; desmin = lamin

Epithelial Tissue

Parenchyma (functional parts of organ)

Simple- one layer

Stratified- multiple layers

Pseudostratified- one layer but looks like multiple

Cuboidal- cube shaped

Columnar- long and narrow

Squamous- flat, scale-like

Connective Tissue

Stroma (support, extracellular matrix). Bone, cartilage, tendon, blood

Capsid

Protein coat

Virion

Individual virus particles

Bacteriophage

Bacteria virus. Tall sheath injects DN/RNA.

If a virus is single stranded

Positive Sense- Can be translated by host cell

Negative Sense- RNA replicase must synthesize a complimentary strand, which can be translated

Retrovirus

Single stranded RNA. Reverse transcriptase needed to make DNA.

Bacteriophage Life Cycles

Lytic: Virions made until cell lyses

Lysogenic: virus integrates into genome as provirus or prophage. Goes dormant until stress activates it.

G1 (Cell cycle)

Make mRNA and proteins to prep for mitosis

G0 (Cell cycle)

A cell will enter this if it does not need to divide

G1 Checkpoint

Cell decided if it should divide. PS3 in charge.

S (Cell cycle)

DNA replicated

G2 (Cell cycle)

Cell growth. Make organelles.

G2 Checkpoint

Check cell size and organelles

M (Cell cycle)

Mitosis and cytokinesis

Positive Growth Signals

1) CDK + cyclin create a complex

2) Phosphorylates Rb to Rb + P

3) Rb changes shape, releases E2F

4) Cell division continues

Negative Growth Signals

1) CDK inhibitors block phosphorylation of Rb

2) So, E2F stays attached

3) Cell cycle halts

Prophase (Mitosis)

DNA condenses. Centrioles migrate to opposite poles and microtubules form. Nuclear envelope disappears.

Metaphase (Mitosis)

“Meet in the middle.” Chromosomes meet in the middle.

Anaphase (Mitosis)

“Apart.” Sister chromatids separate and move to opposite poles.

Telophase (Mitosis)

Chromosomes decondense. Nuclear membrane forms. Cytokinesis occurs.

Nondisjunction

When sister chromatids don’t separate properly during anaphase. Results in aneuploidy.

Prophase I (Meiosis)

Chromosomes condense, nuclear membrane dissolves, homologous chromosomes form bivalents, crossing over occurs

Metaphase I (Meiosis)

Spindle fibers from opposing centrosomes connect to bivalents (at centromeres) and align them along the middle of the cell

Anaphase I (Meiosis)

Homologous pairs move to opposite poles of the cell. This is disjunction and it accounts for the Law of Segregation.

Telophase I (Meiosis)

Chromosomes decondense, nuclear membrane MAY reform, cell divides (cytokines), forms two haploid daughter cells of unequal sizes

Prophase II (Meiosis)

Chromosomes condense, nuclear membrane dissolves, centrosomes move to opposite poles (perpendicular to before)

Metaphase II (Meiosis)

Spindle fibers from opposing centrosomes attach to chromosomes (at centromere) and align them along the cell equator

Anaphase II (Meiosis)

Spindle fibers contract and separate the sister chromatids, chromatids (now called chromosomes) move to opposite poles

Telophase II (Meiosis)

Chromosomes decondense, nuclear membrane reforms, cells divide (cytokinesis) to form four haploid daughter cells

Bulbourethral Gland

Makes viscous fluid to clean out urethra

Seminal Vesicles and Prostate Gland

Make alkaline fluid to help sperm survive acidic environment of female reproductive tract

Follicle Stimulating Hormone

Males: Triggers spermatogenesis, stimulates Sertoli Cells

Females: Stimulates development of ovarian follicles

Luteinizing Hormone

Males: Causes interstitial cells to make testosterone

Females: Induces ovulation

Morula

Early. Solid mass of cells.

Blastula

• Implants in endometrial lining

• Fluid filled blastocoel

• Trophoblast → chorion/placenta

• Inner cell Mass → organism

Ectoderm

Nervous System, skin, hair, nails, mouth anus (“attract-oderm” things people are attracted to)

Mesoderm

Muscoskeleton, circulatory system, gonads, adrenal cortex. (“Move-oderm” involved in moving things such as muscles, red blood cells, and steroids)

Endoderm

Endocrine glands, GI tract, bronchi, bladder, stomach (“In-doderm” things that are inside)

Totipotent

“Total”, can be any type of cell

Pluripotent

Can be any cell except those found in placental structures

Multipotent

More specialized. Can be multiple types of cells.

Determination

Cell commits to becoming a certain type of cell

Differentiation

Follows determination. Selectively transcribe genes appropriate for cell’s specific function

Afferent Neurons

Ascend spinal cord

Interneurons

Between other neurons

Efferent Neurons

Exit spinal cord

Temporal Summations

Same space/different time

Spatial Summation

Different space/same time

Atrocytes

Blood-brain barrier. Controls solutes moving from bloodstream → nervous tissue

Ependymal Cells

The barrier between cerebrospinal fluid and interstitial fluid of the central nervous system

Microglia

Digest waste in central nervous system

Schwann Cells

Peripheral nervous system, makes myelin

Oligodendrocytes

Central nervous system, makes myelin

White Matter

Myelinated sheaths

Grey Matter

Cell bodies and dendrites. Unmyelinated.

Brain

White deep/grey outer

Spinal cord

Grey deep/white outer

Monosynaptic

Sensory neuron → motor neuron

Polysynaptic

Sensory → interneuron → motor

Peptide Hormones

• Made of amino acids

• Cleaved from larger polypeptides

• Golgi modifies and activates hormone

• Put in vesicles released via exocytosis

• Polar so they cannot pass through the membrane, so they use extracellular receptors like GPCR

Steroid Hormones

• Made in gonads and adrenal cortex from cholesterol

• Don’t dissolve, must be carried by proteins

• Non-polar, so can pass through membranes

• Activate nuclear receptors

• Direct action on DNA

Direct Hormones

Act directly on target tissue/organ such as insulin

Trophic Hormones

Require an intermediary. They only affect other endocrine tissues.

Type 1 Diabetes

No insulin, so glucose is not able to enter cells

Type 2 Diabetes

Desensitized insulin receptors. Glucose unable to enter cells.

Calcitonin

Increases calcium in bone and excretion from kidneys. Decreases calcium in blood and absorption in gut.

Total Lung Capacity

Maximum volume of air in the lungs

Residual Volume

Residual after exhalation (air stays in lungs to keep alveoli from collapsing)

Vital Capacity

Difference between minimum and maximum volume of air in the lungs

Tidal Volume

Volume inhaled and exhaled in a normal breath

Expiratory Reserve Volume

Volume of additional air that can be forcibly exhaled following normal exhalation

Inspiratory Reserve Volume

Volume of additional air that can be forcibly inhaled following normal inhalation

Inhalation

• Negative pressure breathing

• Active process

• Diaphragm and external intercostal muscles contract

• Increase in interpleural space, thoracic cavity, and lung volume

• Decreases pressure and lung pressure

• Air rushes in

Exhalation

• Passive process

• Muscles relax

• Decrease lung volume and increase lung pressure

• Air leaves lungs

Respiratory protection from pathogens

• Vibrissae in pharnyx

• Mucous membranes

• Mucociliary escalator

• Lysozymes in nasal cabity/saliva. Attack gram + peptidoglycan

• Mast Cells have antibiotics on surface. Inflammation. Allergic reactions.

Systole

Ventricular contraction, AV valves close

Diastole

Ventricular relaxation, SV close, blood atria → ventricles

Arterioles

Small muscular arteries

Capillaries

1 cell thick endothelial wall, easy diffusion of gases and waste