Biology Flashcards Preview

MCAT > Biology > Flashcards

Flashcards in Biology Deck (56):
1

What is connective tissue?

Provide support/framework for epithelial cells; blood, bone, cartilage, tendons, ligaments, adipose tissues

2

What are the three main parts of Darwin's Theory of natural selection?

1. Organisms produce offspring of few survive. Chance variations within populations are heritable.
2. If the variation increases an organism's survival chances, the variation is termed favorable.
3. These individuals will have greater fitness (reproductive success) and fitness is directly correlated to organism's genetic contribution to the next generation.

3

What are the layers of the skin?

Epidermis, dermis, hypodermis

4

What are the layers of the epidermis?

Corneum (dead skin cells, protection
Lucidum (thick, hairless, hells of palms)
Granulosum (keratonocytes die)
Spinosum (langerhancells, macrophages, present antigens to T- cells)
Basale (stem cells=> keratinocytes; melanocytes --> skin color)

5

What are the layers of the dermis?

Papillary- loose connectice tissue
Reticular- hair follicles, sweat glands, blood vessels

6

What does the hypodermis contain?

Fat = connective tissue

7

What are the sensory receptors of dermis?

Merkel- deep pressure + tecture
Pacinian- deep pressure + vibration
Meissner's - light touch
Ruffini- stretch

8

Where is the electron transport chain located in prokaryotes?

Plasma membrane

9

What is the molecular weight of an amino acid?

110 Da

10

What is commensalism?

one benefits; the other doesn't but doesn't harmed either

11

What is mutualism?

mutually dependent

12

What is parasitism?

one benefits; the other is harmed

13

What is senescence?

biological aging in which cells no longer replicate (shortened telomeres)

14

What does the ectoderm form?

epidermis, NS, adrenal medulla

15

What does the mesoderm form?

dermis, musculoskeletal system, circulatory system, adrenal cortex

16

What does the endoderm form?

epithelial lining of GI and resp systems

17

What is induction?

The release of factors that promote differentiation in other tissues (can be reciprocal)

18

What cells produce myelin in the CNS?

oligodendrocytes

19

What cells produce myelin in the ONS?

Shwann cells

20

upstream and downstream a gene

upstream is before the gene; downstream is after the gene

21

osteoblast

bone-forming cells (build)

22

osteoclasts

bone-resorbing cells (breakdown)

23

vasoconstriction

increases blood pressure but decreases oxygen delivery to those tissues

24

perfusion

the movement of fluid through the circulatory or lymphatic system, specifically the delivery of blood to capillary beds in tissues

25

Myosins

hydrolyze ATP to power sarcomere contract

26

Microtubules

Kinesins and Dynenin; motor proteins involved in intracellular transport; deliver vesicles along MT's (kinesins towards + and dyneins toward -)

27

Eukaryotic cell membranes only have fatty acids with

1) and even number of Carbons
2) only CIS double bonds (NO TRANS AT ALL)

28

each cytochrome c molecule carries

1 electron for it's one heme molecule

29

Primers suitable for PCR have

a high GC content and G and C base pairs at the ends

30

Nondisjunction

failure of homolog chromosomes to separate in Anaphase I or sister chromatids to separate in Anaphase 2

31

Microfilaments

actin

32

Intermediate filaments

keratin, lamins, cell-cell adhesion, anchors

33

What is convergent evolution?

When distantly related organisms independently evolve similar traits to adapt to similar needs.

34

Gene operons in prokaryotic cells

are transcribed from a single promoter upstream the operon and DON'T undergo splicing

35

Imprinted gene

genes expressed in a parent-specific manner

36

What is a silent mutation?

Has no effect on protein

37

What is a missense mutation?

Amino acid substitution

38

What is a nonsense mutation?

Early stop codon

39

What is the start codon?

AUG = Methionine

40

What are the stop codons?

UAA, UGA, UAG

41

What is a chromosomal duplication mutation?

A segment of DNA is copied multiple times

42

What is a chromosomal deletion mutation?

large segment of DNA is lost

43

What is penetrance?

The proportion of population with a certain genotype who actually express the phenotype.

44

What is expressivity?

The diff phenotypic manifestations of a genotype across the population.

45

Fecundity

How easily and frequently and organism can produce offspring.

46

Natural Selection vs Group Selection

natural is selection until reproduction where as group is selection after reproduction (grandparents help raise grandkids)

47

Genetic Drift

composition of gene pool changes due to random chance **small populations**

48

Bottleneck effect

major disaster or event that kills off a large part of the population (extreme form of genetic drift)

49

Founder effect

results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes and less variation in the genotype

50

Divergent evolution

occurs when two species share a common ancestor become more different

51

Parallel evolution

occurs when two species share a common ancestor evolve the same way

52

Convergent evolution

occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressure

53

Punctuated Equilibrium

considers evolution to be a slow process with intermittent rapid bursts of evolutionary activity

54

recombinant frequency

the likelihood of two allele being separated during crossing over in meiosis

55

Hardy-Weinberg principle

if a population meets certain criteria (aimed at lack of evolution) then the allele frequencies will remain constant

56

Reproductive isolation of species: prezygotic mechanisms

temporal (mating season)
ecological (different niches)
behavioral (lack of attraction)
reproductive (parts don't match up)
gametic (intercourse but no fertilization)