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MCAT REVIEW 2021 > BIOLOGY > Flashcards

BIOLOGY Flashcards

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MCAT flashcards
1
Q

CELL THEORY

A
  1. All living things are composed of cells
  2. The cell is the basic functional unit of life
  3. Cells arise only from preexisting cells
  4. Cells carry genetic information in the form of DNA. Passed from parent to daughter cell
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2
Q

Eukaryotes

A

Have membrane bound organelles, nucleus and may from multi cellular organisms

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3
Q

Cytosol

A

Suspends the organelles and allows diffusion of molecules throughout the cell.

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4
Q

Nucleus

A

Control Center. Contains DNA organized into chromosomes. Surrounded by nuclear membrane , that contains nuclear pores for 2 way exchange of materials between the nucleus and cytosol. DNA organized into coding regions called genes.

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5
Q

Nucleolus

A

Subsection of nucleus in which rRNA is synthesized.

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6
Q

Mitochondria

A

Powerhouse of the cell. Membrane bound organelle where reactions of aerobic respiration and ATP synthase occur. Can divide independently of nucleus. Can cause apoptosis.

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7
Q

Lysosomes

A

Membrane bound organelle that stores hydrolytic enzymes. Break down substrates and cellular waste. Prevents damage to cell but can cause autolysis.

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8
Q

Rough Endoplasmic reticulum

A

series of interconnected membranes. RER studded with ribosomes which permit translation of proteins defined for secretion.

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9
Q

Smooth Endoplasmic reticulum

A

series of interconnected membranes. Used for lipid synthesis and detoxification.

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10
Q

Golgi apparatus

A

Consists of stacked membrane bound sacs where cellular products can be modified, packed and directed to specific cellular locations.

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11
Q

Peroxisomes

A

Contain hydrogen peroxide and can break down long Fatty acids via Beta oxidation.

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12
Q

Cytoskeleton

A

Provides stability and rigidity to the overall structure of the cell. Provides transport pathways for molecules within the cell.

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13
Q

Microfilaments

A

Composed of actin. Provide structural protection. Can cause muscle contractions with myosin. Form cleavage furrow during cytokinesis in mitosis

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14
Q

Microtubules

A

Composed of tubulin. Create pathways for motor proteins to carry vesicles. Contribute to structures like cilia and flagella.

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15
Q

Intermediate Filaments

A

Involved in cell to cell adhesions and maintenance of the integrity of the cytoskeleton. Help anchor organelles. Ex: Keratin , desmin.

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16
Q

Epithelial tissues

A

Cover body and line its cavities. Protect against pathogen invasions and desiccation. Classified by layers simple(1), stratified(many) and pseudo stratified ( appear to have many but only have 1). Classified by shapes of cell cuboidal(cubes), columnar (long and narrow) and squamous (flat).

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17
Q

Connective tissues

A

Support body and provide framework for epithelial cells. Bone, Cartilage, tendons, ligaments, adipose tissue and blood are all connective tissues.

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18
Q

Prokaryotes

A

Do not contain membrane bound organelles.Their genetic material in a single circular molecule of DNA located in the nucleiod region.

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19
Q

Archea

A

Live in harsh environments. Use chemical sources of energy. Similar to both Eukaryotes and bacteria

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20
Q

Bacteria

A

Similar structure to Eukaryotes. Complex relationships with humans including mutualistic symbiosis and pathogenesis/parasites. Can be classified by cocci(sphere), Bacilli(rod) and Spirilli(spiral).

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21
Q

Obligate Aerobe

A

Require Oxygen for survival and metabolism

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22
Q

Obligate Anaerobe

A

Can NOT survive in Oxygen containing environment. Can only carry out anaerobic metabolism

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23
Q

Facultative Anaerobe

A

Can survive in environment with or without oxygen. Can do both aerobic and aerobic metabolism.

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24
Q

Aerotolerant Anaerobe

A

cannot use oxygen for metabolism but can survive in oxygen containing environments.

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25
Q

Gram positive bacteria

A

Stain purple. Thick cell wall composed of peptidoglycan and lipoteichoic acid. Penicillin targets the enzymes that catalyzes cross linking of peptidoglycan.

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26
Q

Gram negative bacteria

A

stain pink-red. Thin cell wall composed of peptidoglycan. Outer membrane containing phospholipids and lipopolysaccharides.

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27
Q

Binary Fission

A

Asexual prokaryote reproduction. Circular chromosome attaches to cell wall and replicates while cell continues to grow. Results in 2 identical daughter cells.

28
Q

Genetic Recombination

A

Plasmids.
Helps increase bacterial diversity.
Can lead to antibiotic resistance.

29
Q

Transformation

A

Type of Genetic Recombination. Integration of foreign genetic material into host genome. Many gram negative rods able to carry out this process

30
Q

Conjugation

A

Type of Genetic Recombination. Sexual reproduction. Transfer or genetic material from one bacterium to the other through conjugation bridge. Sex pilli used. Plasmids transferred.

31
Q

Transduction

A

Type of Genetic Recombination. Transfers genetic material from one bacterium to the other via bacteriophage vector.

32
Q

Transposons

A

genetic elements that can insert into or removes themselves form genome.

33
Q

Bacterial growth pattern

A
  1. Lag phase- when first placed in new environment
  2. Exponential (log) phase- growth increases exponentially
  3. Stationary phase- all resources are reduced, growth levels off
  4. Death phase- resources depleted
34
Q

Viruses

A

Obligate intracellular parasites. Need host for replication. Individual particles are called virions

35
Q

Bacteriophages

A

viruses that target bacteria. Have tail sheath and tail fibers.

36
Q

Viral Genomes

A
  1. Can be DNA or RNA, single or double stranded
  2. positive sense- single stranded RNA that can be translated by host cell
  3. negative sense- single stranded RNA requires complementary strand to be synthesized.
  4. Retroviruses - HIV
37
Q

Lytic cycle

A

Bacteriophage life cycle. Bacteriophage produce massive number fo new virions until the cell lyses. e

38
Q

Lysogenic cycle

A

Bacteriophage life cycle. Virus integrates into the hose genome as a provirus or prophage, which can reproduce along with the cell.

39
Q

Prions

A

Infectious proteins that trigger misfolding of other proteins. mostly alpha helices to Beta pleated sheets.

40
Q

Virioids

A

plant pathogens, small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes of cell and potentially cell death.

41
Q

Diploid

A

2n

Cells have 2 copies of each chromosome

42
Q

Haploid

A

n

Cells have 1 copy of chromosome

43
Q

Cell Cycle

A
  1. G1( Pre synthetic cap): cells create organelles for energy & protein production. There is a restriction point where DNA sis checked for quality
  2. S(synthesis): DNA replicated . DNA strands called chromatids are held together at centromere
  3. G2(Post synthetic gap): Further cell growth and replications occur. Other quality check point.
  4. M: Mitosis and cytokinesis occur
  5. G0: The cell performs its functions without preparing for division.
44
Q

P53

A

Plays roll in major check points of cell cycle.

45
Q

Cyclins and cyclin-dependent kinases(CKD)

A

Rise and fall during cell cycle cyclins bind to CKDs, phosphorylating and activating transcription factors for the next stage of the cell cycle

46
Q

Cancer

A

occurs when cell cycle control become deranged allowing damaged cells to undergo mitosis

47
Q

Mitosis

A

Occurs in somatic cells. Produces two genetically identical diploid daughter cells from a single cell. 4 stages Prophase, Metaphase , anaphase, telophase.

48
Q

Mitosis: Prophase

A

Chromosomes condense , nuclear membrane dissolves , nuceloid disappears, centrioles migrate to opposite sides of cell and spindle apparatus begins to form. Kinetochore of each chromosome is contacted by spindle fiber.

49
Q

Mitosis: Metaphase

A

Chromosome line up along the metaphase plate

50
Q

Mitosis: Anaphase

A

Sister chromatid are separate and pulled to opposite poles

51
Q

Mitosis: Telophase

A

Nuclear membrane forms, spindle apparatus disappears, cytosol and organelles are split between two daughter cells through cytokinesis.

52
Q

Meiosis

A

Occurs in gametocytes(germ cells) and produces up to 4 non-identical haploid sex cells (gametes). Has 1 round of replications and 2 rounds of division.

53
Q

Prophase I

A

Same as prophase in mitosis, except that homologues come together and intertwine called synapsis. 4 chromatid are referred to as a tetrad and crossing over exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome. This accounts from Mendel’s second law (law of independent assortment)

54
Q

Metaphase I

A

Homologous chromosomes line up on opposite sides of the metaphase plate.

55
Q

Anaphase I

A

Homologous chromosome are pulled to opposite poles of the cell. This account for Mendel’s first law(segregation)

56
Q

Telophase I

A

Chromosomes may or may not fully decondense and the cell may enter interkinesis after cytokinesis

57
Q

X chromosome

A

carries genetic info, mutations of X-linked genes can cause sex-linked disorders. Males are homozygous with unpaired genes on X chromosome so they will express the sex linked disorder even if they only have one recessive carry allele. Women with 1 copy of the affected allele are called carriers.

58
Q

Y chromosome

A

Carries little genetic info , does contain SRY (sex-determine region) gene, causes gonads to differentiate into testes. XX female, XY male.

59
Q

Male reproductive system

A

Includes Internal and External parts. Testes have 2 functions Sertoli cells that nourish Sperm. Interstitial cells of leydig secrete testosterone. Sperm travels from seminiferous tubules -> Epididymis -> Vas deferens -> Ejaculatory duct -> Urethra -> Penis.
Prostate gland produces alkaline
Bulbourethral glands produce clear viscous fluid that cleans out remnant of urine and lubricates urethra during sexual arousal.

60
Q

Spermatogenesis

A

Development of a mature sperm cells starts as spermatogonium -> primary spermatocyte(after S phase) -> secondary spermatocyte(After Meiosis I) -> Spermatid(After Meiosis II) -> spermatozoan(After Maturation)

61
Q

Sperm structure

A
  1. Head- has genetic info , covered with acrosome , penetrates the ovum
  2. Mid-piece- generate ATP from fructose
  3. Flagellum- promotes motility
62
Q

Female reproductive system

A

Only contains internal structures

  1. Ova(eggs) are produced in follicles the ovaries
  2. once a month the egg is ovulated into the peritoneal sac and is drawn into the fallopian tube
  3. Fallopian tube connected to the uterus and lower end of which is the cervix
  4. Vaginal canal lies below the cervix and site where sperm is deposited
  5. vulva is name for external female anatomy
63
Q

Oogenesis

A

Development for the egg.
Primary oocyte are in Prophase I -> Secondary oocyte is the ovulated egg each month in metaphase II -> fertilized oocyte will complete in meiosis II ->

64
Q

Gonadotropin-releasing hormone (GnRH )

A

1.From the hypothalamus releases FSH and LH. Those hormones act differently dependent on sex

65
Q

Four Stages of Menstrual Cycle

A
  1. Follicular: FSH causes growth of a follicle
  2. Ovulation: LH causes follicle to release egg
  3. Luteal: corpus luteum forms
  4. Menstruation: endometrial lining sheds
66
Q

Menopause

A

occurs between aged 45-55 when ovaries stop producing estrogen and progesterone. Physical and physiological changes may occur.

MCAT REVIEW 2021 (6 decks)

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