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Biology > Topic 2- Gas Exchange, Proteins, Inheritance > Flashcards

Topic 2- Gas Exchange, Proteins, Inheritance Flashcards

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1
Q

Describe features of mammalian lungs that increase rate of gas exchange. (4)

A
  1. Lots of alveoli means large SA for diffusion to occur across
  2. Alveolar and capillaru epithelium are only 1 cell thick (short diffusion pathway)
  3. Alveoli have good blood supply from capillaries (constantly take away O2 and bring more CO2)
    -maintains conc. gradient
  4. Breathing in and out keeps conc.gradient high
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2
Q

What does cholesterol do in the phospholipid bilayer?

A

Forms bonds between phospholipids to make cell membrane more rigid (maintains fluidity)

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3
Q

What are glycoproteins?

A

-protein with a polysaccharide chain attached
-involved in cellular recognition

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4
Q

What are glycolipids?

A

-lipid w/ polysaccharide chain attached
-involved in cellular recognition

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5
Q

Why is the cell surface membrane ‘fluid’?

A

phospholipids are constantly moving allowing fro proteins to move within it

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6
Q

Describe what happens to the cell membrane when temp. below 0ºc. (3)

A
  1. phospholipids have low kinetic energy so don’t move around as much= more rigid and closely packed
  2. channel and carrier proteins deform= increase permeability
  3. ice crystals can pierce the membrane= more permeable
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7
Q

Describe what happens to the cell membrane between 0 and 45ºc (2)

A
  1. phospholipids have kinetic energy and can move around= aren’t tightly packed together so partially permeable
  2. increase in temp.= phospholipids move more= more permeable membrane
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8
Q

Describe what happens to the cell membrane above 45ºc (3)

A
  1. phospholipid bilayer starts to melt= more permeable
  2. water inside cell expands and puts pressure on membrane
  3. channel and carrier proteins denature and can’t control what enters/ exits the cell = increase permeability
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9
Q

What is the effect of alcohol conc. on membrane permeability?

A
  • alcohol dissolves the lipids in the cell so membrane loses its structure= more permeable
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10
Q

Name all the bonds in primary and secondary protein structure.

A
  • primary= held by peptide bonds between amino acids
  • secondary= hydrogen bonds form between amino acids in a chain (alpha helix/ beta pleated sheet)
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11
Q

What are the bonds in tertiary structure?

A
  1. ionic bonds= attractions between -ve and +ve charges on diff. parts of molecule
  2. disulfide bonds= when amino acid cysteine is near another cysteine, a sulfur atom from bonds to sulfur in the other
  3. hydrophilic/ hydrophobic interactions= hydrophobic groups clump together and hydrophilic groups pushed to outside
  4. H bonds
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12
Q

Describe the structure of DNA

A
  1. 2 DNA polynucleotide strands join by H bonding between complementary bases
    • 2 H bonds for A-T/ 3 H bonds for C-G
  2. two antiparallel polynucleotide strands twist to form DNA double helix
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13
Q

What is a gene?

A
  • sequence of mononucleotide bases on a DNA molecule that code for a sequence of amino acids in a polypeptide
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14
Q

What is mRNA?

A
  • made in the nucleus
  • carries genetic code from DNA in the nucleus to cytoplasm for translation
  • DNA is too big to move out of the nucleus
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15
Q

Describe the Genetic Code.

A
  1. sequence of base triplets (codons) in DNA/ mRNA which codes for an amino acid
  2. Non-overlapping= each codon is read once, separate from the triplet before and after it
  3. Degenerate= more combinations of triplets than amino acids (only 20) so some amino acids are coded by more than one triplet
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16
Q

Describe the replication of DNA. (5)

A
  1. enzyme DNA helicase breaks H bonds between the two polynucleotide DNA strands= unwinds
  2. each OG strand acts as a template for new strand
    • complementary base pairing means free floating DNA nucleotides are attracted to exposed complementary base
  3. Condensation reactions join nucleotides of new strands together which is catalysed by DNA polymerase
  4. H bonds form between bases of OG and new strands
  5. each new DNA molecule contains one strand of OG and one new
17
Q

Describe Meselson and Stahl’s evidence for semi conservative replication

A
  1. 2 samples of bacteria were grown= one in N14 (light) and one in N15 (heavy) broth
  2. as bacteria reproduced they took up the N to make nucleotides so N was incorporated into bacteria’s DNA
  3. each sample of DNA was put in centrifuge and bacteria with heavy N DNA settled lowe
  4. bacteria grown only in in heavy broth was put in only light N broth = left for one round of DNA replication
  5. another DNA sample taken and spun and found DNA settled in the middle = so DNA contained a mixture of light and heavy N DNA
  6. if it was conservative= light DNA band above the heavy DNA band
18
Q

What is meant by semi conservative and conservative replication?

A
  • conservative= original DNA strands stay together while new DNA molecules contain two new strands
  • semi conservative= new DNA molecules contain one strand of OG and one strand of new
19
Q

What are the 5 mutations that can occur during DNA replication?

A
  • substition = one base is subbed for another
  • deletion= one base is deleted
  • insertion= an extra base is added
  • duplication= one or more bases are repeated
  • inversion= a sequence of bases is reversed
20
Q

Why is DNA replicated?

A
  • DNA must copy itself before cell division so each new cell has full amount of DNA
  • ensures genetic continuity between generations of cells
21
Q

What is incomplete dominance?

A
  • when the trait from the dominant allele isn’t fully shown over the recessive trait
  • both alleles influence phenotype
22
Q

What is the chi-squared test and what is the null hypothesis for it?

A
  • statistical test that’s used to see if results of an experiment support a theory
  • null hypo= no significant difference between the observed and expected results
23
Q

How to compare chi-squared value to critcal value

A
  • degrees of freedom= no. classes -1
  • critical value corresponding to probability of 0.05
  • if x2 is higher or equal to critical value the null hypothesis is rejected (something other than chance is causing the difference between observed and expected results)
24
Q

What is cystic fibrosis?

A
  • inherited disorder affecting digestive, respirotory and reproductive systems (caused by a recessive allele)
  • mutation in a gene that codes for CFTR protein which is a channel protein transporting Cl- out of cells and into mucus
  • Cl- causes water to move into mucus via osmosis
  • mutant CFTR proteins are less effient in transporting Cl- out so mucus is abnormally thick and sticky
25
Q

What does CFTR stand for?

A

Cystic Fibrosis Transmembrane conductance Regulator

26
Q

How does CF affect the respirotory system?

A
  • cilia unable to move mucus towards throat to be swallowed and it’s too thick + sticky
  • mucus builds up in airways and may completely block them
  • reduces SA for gas exchange= breathing difficulties
  • people w/ CF are more prone to lung infections as trapped microorganisms in mucus aren’t removed
27
Q

How does CF affect the digestive system?

A
  1. tube connnecting pancreas to small intestine can become blocked
    - prevent digestive enzymes from reaching small intestine and lowers digestion of food
    - less nutrients absorbed
  2. mucus can also cause cysts in pancreas and inhibit production of enzymes
  3. mucus lining small intestine is too thick so less nutrients absorbed
28
Q

How does CF affect the reproductive system?

A
  1. tubes connecting testicles to penis are absent and can be blocked by mucus from others (sperm can’t reach penis)
  2. thickened cervical mucus prevents sperm reaching egg and it reduces mobility of sperm
29
Q

What is a sex linked gene?

A
  • gene responsible for a trait that is located on a sex chromosome
  • expression of the gene is related to sex/gender
30
Q

What are the similarities and differences between transcription + replication?

A

similarities = both use DNA helicase and form phosphodiester bonds between nucleotides
differences
- RNA polymerase used in transcribtion, and DNA polymerase in replication
- DNA nucleotides in replication, RNA in transcription
- replication produces a double stranded DNA molecule and transcription forms mRNA

31
Q

What is an inherited recessive disorder?

A
  • one caused by a faulty gene
  • only expressed in the homozygous recessive genotype
32
Q

Describe the 2 Prenatal Tests

A
  1. Amniocentesis (15-20 weeks of pregnancy)
    - sample obtained from amniotic fluid containing fetal cells
    - 1% risk of miscarriage and long wait time
  2. Chorionic Villus Sampling (11-14 weeks if pregn)
    - sample taken from chorionic villi containing DNA for analysis
    - quicker results so an earlier decision can be made but 1-2% chance of miscarriage
33
Q

Describe the two types of genetic screening that are not prenatal testing

A
  1. Identification of carriers= offered to those who have a family history of genetic disorders to find out if they are carriers of the disease
    - helps make informed decisions but could cause discrimination from life insurance companies
  2. Preimplantaion Genetic Diagrams= on embryos for IVF before implantation
    - avoids issue of abortion and chance the baby has disorder
    - can have false results and lead to designer babies ( embryos selected for certain characteristics)
34
Q

Describe the structure of the cell surface membrane

A
  • made mostly of phospholipids and proteins
  • forms a bilayerr
  • fluid mosaic model with proteins that can move within it
  • intrinsic or extrinsic proteins

Biology (8 decks)

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