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Biology 102 > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

Nucleotides

A
  • monomers of nucleic acid chains (polymers)
  • made up of: phosphate group, 5-carbon sugar, nitrogen-containing base (thymine, cytosine, adenine, guanine)
  • ribonucleotides in RNA, deoxyribonucleotides in DNA
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2
Q

Nucleic Acid Polymers

A
  • DNA (found in chromosomes): carries genetic information for protein construction; double helix, “steps” are stronger together than apart (hydrogen bonds)
  • RNA: copies of DNA used directly in protein construction (has uracil instead of thymine)
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3
Q

Genes and DNA

A
  • heritable information is carried in discrete units called GENES
  • genes are parts of structures called CHROMOSOMES
  • chromosomes are made of DNA and PROTEIN
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4
Q

Genes

A

can transform other material

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5
Q

Chargaff’s Rule

A

in a DNA molecule, A bonds to T and G bonds to C through hydrogen bonds (easily formed, easily broken)

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6
Q

DNA Structure

A
  • long and thin; has a uniform diameter of 2 nanometers. must be condensed/coiled to fit into nucleus for easy manipulation in cell division
  • is helical, twisted like a corkscrew/ladder, and made of 2 strands of nucleotides; twisted into double helix
  • the deoxyribose and phosphate portions makes up the sugar-phosphate backbone; nitrogen-containing bases (repeating subunits) protrude inward from this
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7
Q

Chromosomes

A
  • each chromosome consists of a DNA double helix wound around spool proteins
  • genes are part of chromosomes, not the other way around
  • 23 pairs per person or 46 total - 23rd is sex chromosome
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8
Q

Central Dogma

A

DNA is read and synthesized/translated to protein through DNA replication (unzipping - guided by enzymes) - size and length matters

DNA information must be carried by an intermediary (mRNA) from nucleus to the cytoplasm
- DNA –> mRNA –> protein

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9
Q

Transcription vs. Translation

A
  • transcription: to make a copy (when the information in a DNA gene is copied into RNA)
  • translation: to translate that copy (mRNA with tRNA, amino acids, and a ribosome synthesize a protein)
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10
Q

Semi-Conservative Replication

A

new strand contains half of old one; two resulting DNA molecules have one old parental strand and one new strand/two identical DNA double helixes from one DNA double helix

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11
Q

Messenger RNA (mRNA)

A

what DNA is transcribed onto; once synthesized, leaves nucleus and attaches to ribosome (not double-stranded - single-sided)

  • intermediary, complementary copy of DNA, only reads one side of DNA, thymine changes to uracil
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12
Q

Telomeres

A

“end bodies,” “caps” or two ends of a chromosome; essential in maintaining chromosome stability

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13
Q

Karyotype

A
  • entire set of chromosomes, shows pairs
  • homologous chromosomes: “partner” of every chromosome in a nonreproductive cell
  • homologues contain similar genes: size, shape, banding pattern
  • duplicated chromosomes are tightly coiled “x” shapes
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14
Q

DNA Replication

A
  • duplication of the parent DNA
  • begind when DNA HELICASE separates or unzips the two strands, hydrogen bonds between bases are broken
  • a second strand of new DNA is synthesized along each separated strand by DNA polymerases, which position free nucleotides across from complementing ones
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15
Q

DNA Repair

A
  • DNA polymerase mismatches nucleotides once every 10,000 base pairs
  • DNA repair enzymes “proofread” each new daughter strand, replacing mismatched nucleotides
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16
Q

DNA Damage

A
  • easily damaged; spontaneous breakdown at body temperature, certain chemicals, UV light from sun
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17
Q

Mutations

A
  • point mutation: individual nucleotide in the DNA sequence is changed (substitution)
  • insertion mutation: one or more nucleotide pairs are inserted into the DNA double helix
  • deletion mutation: one or more nucleotide pairs are removed from the double helix (most potentially damaging)
  • inversion: piece (“chunk”) of DNA is cut out of a chromosome, turned around, and re-inserted into the gap
  • translocation: chunk of DNA (often very large) is removed from one chromosome and attached to another
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18
Q

DNA and Protein

A
  • DNA contains the molecular blueprint of every cell
  • proteins are the “molecular workers” of the cell
  • proteins control cell shape, function, reproduction, and synthesis of biomolecules
  • the information in DNA genes must, therefore, be linked to the proteins that run the cell
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19
Q

RNA vs. DNA

A

RNA is: single-stranded, uses sugar ribose, uracil instead of thymine

20
Q

The Genetic Code

A
  • bases in mRNA are read by the ribosome in triplets called codons
  • each codon specifies a unique amino acid in the genetic code
  • each mRNA also has a start and a stop codon
21
Q

3 types of RNA in Protein Synthesis

A
  • Messenger RNA (mRNA): carries DNA gene information to the ribosome (architectural drawings)
  • Transfer RNA (tRNA): brings amino acids to the ribosome (raw materials)
  • Ribosomal RNA (rRNA): part of the structure of ribosomes (factory)
22
Q

Helicase

A
  • enzyme that splits or unzips the DNA
23
Q

Polymerase

A
  • enzyme that brings DNA together (RNA polymerase breaks apart, synthesizes new strip)
24
Q

Transfer RNA (tRNA)

A
  • carries specific amino acid to a ribosome in protein synthesis
  • anticodon pairs with mRNA codon
  • each tRNA is specific to only one amino acid
25
Q

DNA Transcription: Initiation Phase

A

1) DNA molecule is unwound and strands are separated at the beginning of the gene sequence
2) RNA polymerase binds to promoter region at beginning of a gene

26
Q

Protein Synthesis

A

DNA –> mRNA –> tRNA –> protein

27
Q

Cell Theory

A

1) all organisms are composed of one or more cells
2) cell are the smallest living things
3) all organisms living today represent a continuous line of descent
4) cell arise only by division of a previously existing cell

  • 3) and 4) are most important in discussion of meiosis and mitosis
28
Q

Eukaryotes vs. Prokaryotes

A
  • primary difference: membrane-bound nucleus and organalles

- eukaryotic cells have double membranes

29
Q

Cell Division

A
  • purpose: growth and development
  • differentiate: becoming specialized for specific functions, after division
  • cell cycle: the repeating pattern of division, growth, differentiation, division again
30
Q

3 Categories of Cells

A

most multicellular organisms: stem cells, other cells capable of division (i.e. liver cells), permanently differentiated cells (i.e. heart, brain cells)

31
Q

Cellular Reproduction

A
  • cell cycle: intracellular activity between one cell division to the next (involves growth of the cell and duplication of genetic material and cellular division aka reproduction)
  • asexual reproduction: from a single parent (disadvantages: low genetic diversity, vulnerable; benefits: fast reproduction)
32
Q

Prokaryotic Cell Division

A

simpler, more straightforward

1) long-growth phase: circular DNA chromosome replicated, duplicate chromosomes anchor to membrane
2) cell increases, pulling chromosomes apart
3) plasma membrane grows inward between chromosome copies
4) fusion of membrane along cell equator completes separation (binary fission or splitting in two)
5) daughter cells are genetically identical

33
Q

Eukaryotic Cell Division

A
  • Mitosis: the mechanism of asexual reproduction in eukaryotic ells
  • Meiosis: in animal ovaries and testes, for sexual reproduction in eukaryotes
  • two stages: interphase, cell division (one copy of every chromosome and half of cytoplasm and organelles parceled out into two daughter cells)
34
Q

Mitosis

A
  • normal process of cell division in the body, occurs in somatic cells (a typical cell in the body that is not a germ cell)
35
Q

Stages of Mitosis

A 
Interphase
Prophase (condense)
Metaphase (attach and align)
Anaphase (separate)
Telaphase (cytokinesis)
36
Q

Interphase (of Mitosis)

A
  • most of the time
  • acquisition of nutrients, growth, chromosome duplication
  • G1 (growth phase 1): acquisition of nutrients and growth to proper size
  • S (synthesis phase): DNA synthesis occurs, replicating every chromosome
  • G2 (growth case 2): completion of growth and readying for division
37
Q

Human Body Cells

A

have 23 pairs (diploid) of chromosomes - and every time our body cells reproduce (divide), each NEW cell must also end up with 23 pairs of chromosomes

38
Q

Chromosomal Components

A

1) chromatid
2) centromere
3) short arm
4) long arm

39
Q

Meiosis

A
  • “to make smaller”
  • meiotic cell division is nuclear division, and two rounds of cytokinesis
  • two divisional steps produce four daughter cells that can become gametes (sperm and eggs)
  • daughter cells are genetically different from the parent cell and from each other
  • each daughter cell has half the genetic material of the parent cell (CELL REDUCTION DIVISION)
  • in sexual reproduction, parents generate specialized sex cells called gametes, or germ cells. Reproductive organs produce these cells via meiosis
  • a germ cell has only one copy of each chromosome
  • human unfertilized egg = haploid (23 chromosomes)
  • sperm = haploid (23 chromosomes)

46 chromosomes in each somatic cell (humans)

40
Q

Meiosis Process

A
  • Meiosis 1: separates homologous chromosomes into two haploid daughter nuclei (each receives one copy of each pair)

Meiosis II: separates sister chromatids into four gametes

41
Q

Meiotic Prophase I

A

1) each chromosome has been duplicated during interphase before meiosis starts
2) homologous chromosomes pair up
3) crossing over (genetic recombination): enzymes facilitate exchange of DNA between arms of adjacent chromatids, producing chiasmata

42
Q

Meiotic Metaphase I

A

1) spindle microtubules attached to kinetochore regions of duplicated chromosomes in prophase I
2) duplicated homologous chromosomes are pulled into a line perpendicular to the spindle

43
Q

Meiosis Metaphase vs. Mitosis Metaphase

A
  • duplicated chromosomes line up singly during mitotic metaphase
  • duplicated homologous pairs line up 2-abreast during meiotic metaphase I
44
Q

Diploid

A

a cell that contains two copies of each type of chromosome in its nucleus (except the sex chomosome)

45
Q

Germ cells

A

a sperm or egg (ovum) cell or their precursors - the haploid gametes produced by individuals that fuse to form a new individual

46
Q

Haploid

A

having only 1 copy of a chromosome; a human haploid has 23 chromosomes

47
Q

Gamete

A

a specialized sex cell that is haploid in the male (sperm) and the female (egg)

Biology 102 (4 decks)

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