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Topic 2 completed Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define diffusion

A

the net movement of particles from an area of high to low concentration

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2
Q

is diffusion active or passive?

A

passive- no energy needed

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3
Q

how are the lungs adapted for gas exchange?

A

-lots of alveoli for large surface area
-alveolar epithelium and capillary endothelium are both 1 cell thick (short diffusion pathway)
-alveoli have good blood supply so maintain concentration gradients of gases
-constant breathing keeps concentration gradients constant

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4
Q

what is Fick’s Law?

A

rate of diffusion∝ area of diffusion surface x difference in concentration / diffusion distance

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5
Q

what model is used to describe the cell membrane?

A

fluid mosaic model

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6
Q

what is the layer in a cell membrane?

A

phospholipid bilayer

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7
Q

what is a phospholipid bilayer made of?

A

hydrophilic phosphate heads and hydrophobic fatty acid tails

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8
Q

how is the phospholipid bilayer arranged?

A

fatty acid tails on the inside and phosphate heads on the outside

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9
Q

what 5 additional things can be found in the cell membrane?

A

glycolipids, glycoproteins, cholesterol, protein channels, proteins

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10
Q

define osmosis

A

diffusion of water molecules across a partially permeable membrane from high to low water concentration

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11
Q

what is facilitated diffusion?

A

large and/or charged particles use carrier or channel proteins to move through the cell membrane- down concentration- passive process

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12
Q

how do carrier proteins work?

A

large molecule attaches to protein in membrane, protein changes shape, molecule released to opposite side of membrane

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13
Q

how do channel proteins work?

A

charged molecule diffuses down pores created by channel proteins through membrane

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14
Q

define active transport

A

uses energy to move molecules and ions across plasma membranes against a concentration gradient

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15
Q

how does active transport work?

A

molecule attaches to carrier protein, protein changes shape, molecule released on other side, ATP is hydrolysed which releases energy used to changed the shape of the protein

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16
Q

define endocytosis

A

membrane surrounds large molecule, membrane pinches off to form a vesicle inside the cell- active process

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17
Q

define exocytosis

A

vesicles pinch off from the sacs of the Golgi apparatus and move towards membrane, vesicles fuse with membrane and content is released- active process

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18
Q

how do the largest molecules such as carbohydrates, lipids etc enter and leave the cell?

A

endo and exocytosis

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19
Q

what is the difference between facilitated diffusion and active transport?

A

diffusion both carrier and channel proteins, active transport only uses carrier proteins. facilities diffusion is down concentration but active transport is against the concentration gradient

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20
Q

what is an animo acid made of?

A

a carboxyl group, amine group, H and an R group

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21
Q

how are polypeptides formed?

A

two amino acids join together in a condensation reaction to lose a water molecule and form a polypeptide bond

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22
Q

what is the primary structure of a protein?

A

sequence of amino acids in the polypeptide chain

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23
Q

what is the secondary structure of a protein?

A

hydrogen bonds form alpha helix or beta pleated sheets between the polypeptide chains

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24
Q

what is the tertiary structure of a protein?

A

extra bonds such as ionic or disulphide form, this is the final 3D structure

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25
Q

what is the quaternary structure of a protein?

A

the way several polypeptide chains are held together (more than one chain)

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26
Q

are globular or fibrous proteins soluble?

A

globular

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27
Q

are globular or fibrous proteins a coil?

A

fibrous

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28
Q

where are fibrous tissues found?

A

in connective tissue

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29
Q

are globular or fibrous proteins insoluble?

A

fibrous

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30
Q

what type of protein is haemoglobin?

A

globular

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31
Q

what type of protein is collagen?

A

fibrous

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32
Q

what are enzymes?

A

biological catalysts

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33
Q

what are the 2 models for enzyme activity?

A

lock and fit, and induced fit

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34
Q

how is the induced fit model different to the lock and key model?

A

in the lock and key, neither the enzyme nor the substrate change shape but in the induced fit the substrate has to change the shape of the active site correctly

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35
Q

how does enzyme concentration affect rate of reaction?

A

the more enzyme molecules, the more active sites and therefore the more likely a substrate molecule is to collide with an active site and form a complex. If substrate concentration is limited there comes a point that no more complexes can form as not enough substrate.

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36
Q

how does substrate concentration affect rate of reaction?

A

the more substrate, the more frequent successful collisions and rate increases. until all active sites are full and enzymes become limiting factor

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37
Q

in a nucleotide, what does the oval, pentagon and rectangle represent?

A

oval= phosphate
pentagon= sugar (ribose or deoxyribose)
rectangle= base

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38
Q

what are the bases in DNA?

A

adenine, thymine, cytosine, guanine

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39
Q

what are the bases in RNA?

A

adenine, uracil, cytosine, guanine

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40
Q

what type of bond is between a sugar of one nucleotide and a phosphate of another?

A

phosphodiester (from condensation reactions)

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41
Q

what are the purine bases?

A

adenine and guanine

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42
Q

what are the pyrimidine bases?

A

cytosine, thymine and uracil

43
Q

how many hydrogen bonds between A and T?

A

2 hydrogen bonds

44
Q

how many hydrogen bonds between C and G?

A

3 hydrogen bonds

45
Q

what sort of pairing is between bases?

A

complementary base pairing

46
Q

what makes up a DNA double helix?

A

2 antiparallel polynucleotide strands twisted together

47
Q

describe mRNA

A

messenger RNA-
made in the nucleus during transcription
carries genetic code from DNA in nucleus to cytoplasm

48
Q

describe tRNA

A

transfer RNA-
in cytoplasm
has an amino acid binding site, and a sequence of 3 bases (anticodon)
carries the amino acids that are used to make proteins to the ribosomes during translation

49
Q

the genetic code is non-overlapping, what does this mean?

A

each triplet is read in sequence and separate from the triplets either side

50
Q

the genetic code is degenerate, what does this mean?

A

some amino acids are coded for by more than one codon (more possible combinations of triplets than amino acids)

51
Q

what are the steps of transcription?

A

-RNA polymerase attaches to DNA
-DNA unwinds due to H bonds breaking
-template strand is used to make mRNA using free floating mononucleotides
-RNA polymerase reaches stop codon and
hydrogen bonds reform
-mRNA moves out of nuclear pore and to a ribosome in the cytoplasm

52
Q

what are the steps of translation?

A

-mRNA attaches to ribosome
-tRNA carry amino acids to ribosome
-the tRNA with an anticodon complementary to the start codon attaches to mRNA
-second tRNA does the same
-the 2 amino acids on the tRNA molecules join together to start a polypeptide chain
-once the tRNA molecules are empty they move away
-this continues until a stop codon is reached

53
Q

what are the steps of semi-conservative replication?

A

-DNA helicase breaks hydrogen bonds and DNA unwinds
-both strands act as template strands
-free-floating DNA nucleotides are attracted to exposed bases
-condensation reactions join nucleotides together
-hydrogen bonds form between bases
-2 DNA molecules are produced each with 1 new and 1 old strand

54
Q

who provided evidence for semi-conservative replication?

A

Meselson and Stahl

55
Q

what is the first stage of Meselson and Stahl experiment?

A

grow 2 samples of bacteria, one in N14 and one in N15

56
Q

In the Meselson and Stahl experiment, why do the DNA become different weights?

A

when growing, the bacteria take up the nitrogen into nucleotides for new DNA- the nitrogen are different weights

57
Q

In the Meselson and Stahl experiment, during the first spin what is shown?

A

The DNA from the heavy nitrogen settled lower than the DNA from the light nitrogen

58
Q

in the Meselson and Stahl experiment what happens after the first spin?

A

the bacteria with heavy DNA is put in the light nitrogen for one replication and spun again

59
Q

In the Meselson and Stahl experiment what does the second spin show?

A

the new DNA has one heavy and one light strand and so settled in the middle of the light and heavy DNA

60
Q

what are the 5 types of mutation of DNA?

A

substitution, deletion, insertion, duplication and inversion

61
Q

what is a substitution mutation?

A

one base is substituted for another

62
Q

what is a deletion mutation?

A

one base is deleted- creates a frame shift

63
Q

what is an insertion mutation?

A

an extra base is added- creates a frame shift

64
Q

what is a duplication mutation?

A

one or more bases are repeated

65
Q

what is an inversion mutation?

A

a sequence of bases is reversed

66
Q

define gene

A

a sequence of bases on a DNA molecule, that codes for a protein, which results in a characteristic

67
Q

define allele

A

a different version of a gene (slightly different base sequences so code for different versions of the same characteristic)

68
Q

define genotype

A

the alleles a person has

69
Q

define phenotype

A

the characteristics displayed by an organism

70
Q

define dominant

A

an allele whose characteristic appears in the phenotype even if there’s only one copy

71
Q

define recessive

A

an allele whose characteristic only appears in the phenotype if 2 copies are present

72
Q

define incomplete dominance

A

when the trait from a dominant allele isn’t completely shown over the trait produced by the recessive allele, so both alleles influence phenotype

73
Q

define homozygote

A

an organism that carries 2 copies of the same allele for a certain characteristic

74
Q

define heterozygote

A

an organism that carries 2 different alleles for a certain characteristic

75
Q

define carrier

A

if a recessive allele can cause disease, a carrier is someone who dominant and one recessive allele

76
Q

what is monohybrid inheritance?

A

the inheritance of a single characteristic controlled by different alleles

77
Q

what does chi-squared test?

A

used to see if the results support a theory (to see if the null hypothesis will be accepted or rejected)

78
Q

when using chi-squared, to reject the null which number has to be larger?

A

the x squared number (the number you worked out) has to be larger than the critical value at the 5% significant level

79
Q

what allele is cystic fibrosis caused by?

A

a recessive allele

80
Q

what causes cystic fibrosis?

A

CFTR (cystic fibrosis transmembrane conductance regular) protein

81
Q

what is CFTR?

A

a channel protein that transports chloride ions out of the cell and into mucus

82
Q

how does the mutant CFTR protein cause thick sticky mucus?

A

the mutant protein is less efficient at transporting chloride ions out of the cells (through the basal membrane), so less water moves out by osmosis

83
Q

What 3 systems are affected by cystic fibrosis?

A

respiratory, digestive, reproductive

84
Q

how does sticky mucus affect the respiratory system?

A

cilia are not able to move mucus so it builds up in airways, some airways can become completely blocked. This reduces surface area for gas exchange and causes breathing issues
people with CF also more prone to lung infections as mucus containing microorganisms can not be removed

85
Q

how does sticky mucus affect the digestive system?

A

the tube that connects the pancreas to the small intestine can become blocked- this prevents digestive enzymes produced by the pancreas reaching the small intestine (fewer nutrients are absorbed)
the mucus can cause cysts to form in the pancreas inhibiting the production of enzymes which reduces digestion and absorption of nutrients
the mucus lining of the small intestine is abnormally thick (fewer nutrients absorbed)

86
Q

how does sticky mucus affect the reproductive system in females?

A

thicken cervical mucus can prevent the sperm form reaching the egg as the mucus reduces the mobility of the sperm

87
Q

how does sticky mucus affect the reproductive system in males?

A

the vas deferens (sperm duct) gets blocked with mucus so sperm cannot leave the testes

88
Q

what does genetic screening involve?

A

analyses DNA to see if it contains alleles for genetic disorders

89
Q

what are the 3 uses of genetic screening?

A

identification of carriers, preimplantation genetic diagnosis, prenatal testing

90
Q

what are the ethical issues of carrier testing?

A

founding out you’re a carrier may cause emotional stress or affect your ability to find a partner
tests aren’t 100%- false results possible
other genetic abnormalities could be found which could cause stress
there are concerns that life insurance companies or employers may use the results, causing genetic discrimination

91
Q

what are the positives of carrier testing?

A

offered to people with a family history of genetic disorders so they can determine the chances of any future children having the disease
allows people to make informed decisions

92
Q

what is Preimplantation genetic diagnosis?

A

screens embryos for genetic disorders before they are implanted

93
Q

what are the positives of preimplantation genetic diagnosis?

A

reduces chance of having a baby with the genetic disorder as embryos with the allele for the disorder will not be implanted
avoids potential need for abortion

94
Q

what are the issues with preimplantation genetic diagnosis?

A

can be used to find out other features such as eye colour and may lead to designer babies
false results possible

95
Q

what is prenatal testing?

A

screens foetuses for genetic disorders and are offered to women with a history of genetic disease

96
Q

what are the 2 types of prenatal testing?

A

chorionic villus sampling (CVS) and amniocentesis

97
Q

when is amniocentesis carried out?

A

15-20 weeks of pregnancy

98
Q

what is amniocentesis?

A

A sample of amniotic fluid is obtained using a needle
the fluid contains metal cells which contain DNA which can be analysed

99
Q

what are the disadvantages of amniocentesis?

A

1% risk of miscarriage
takes time- rapid test 3-4 days
full results- 2-3 weeks

100
Q

when is chorionic villus sampling carried out?

A

11-14 weeks of pregnancy

101
Q

what is chorionic villus sampling?

A

a sample of cells is taken from the chorionic villi using a needle and the DNA within the cells is analysed

102
Q

what are the advantages of chorionic villus sampling?

A

takes place sooner than amniocentesis so abortion would be less traumatic

103
Q
A

Biology (9 decks)

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