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BIOL 2030 > DNA & Chromosomes > Flashcards

DNA & Chromosomes Flashcards

1
Q

define genetic library

A

where most genes in a cell are contained

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2
Q

what is a nuclear membrane; what is another name for it

A

2 concentric membranes that separates the nucleus from the cytoplasm; nuclear envelope

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3
Q

define nuclear pores

A

selective channels through the nuclear envelope, allowing some substances thru

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4
Q

define nucleolus

A

the site of ribosomal RNA synthesis and assembly to ribosomal subunits

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5
Q

chromosomes

A

long strand of DNA and protein which can divide

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6
Q

DNA replication

A

provides a “mechanism for heredity” and cell division

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7
Q

gene expression

A

process of converting gene’s nucleotide sequence to amino acid sequence

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8
Q

what is The Genome

A

complete set of info in an organism’s DNA

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9
Q

what composes a nucleotide

A
  • pentose sugar
  • phosphate group
  • nitrogenous base
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10
Q

how many nucleotides make a DNA molecule

A

2

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11
Q

what are some properties of DNA

A
  • sugar-phosphate backbone
  • chemical polarity
  • complementary base pairing
  • antiparallel strands
  • double-helix
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12
Q

describe the bonding of purines with pyramidines

A
  • a pairs with t using 2 h bonds
  • g pairs with c using 3 h bonds
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13
Q

what direction do the nitrogenous bases point on DNA structure

A

toward centre of helix

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14
Q

define mitotic chromosomes

A

chromosomes in their most compressed form

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15
Q

what are challenges chromosomes face

A
  • packaging (greater length of DNA per human cell than diameter of cell nucleus)
  • accessibility
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16
Q

are DNA strands always tightly packed?

A

only during cell division (mitosis)

17
Q

what do chromosomes do that helps cells to condense them

A

chromosomes wrap around specialized proteins

18
Q

How do eukaryotic cells manage to package DNA molecules into compact chromosomes – yet still keep it accessible for replication?

A

thru formation of chromatin, which can change structure when needed

19
Q

what are histones

A
  • proteins that are responsible for first level of DNA packing in chromatin
  • they tightly ionically bind to DNA
20
Q

what is a nucleosome; what is it a basic unit of

A
  • DNA wrapped around histone proteins
  • basic unit of chromatin structure
21
Q

are nucleosomes inside nucleotides, or the other way around

A

nucleosomes include ~200 nucleotide DNA pairs

22
Q

what type of a charge does DNA have and how does that affect the proteins it wraps around

A
  • negative charge (b/c of P groups in backbone)
  • will wrap around positively charged proteins (amino acids like lysine, arginine)
23
Q

describe steps of DNA packing with chromosomes

A
  • short region of DNA double helix condenses into string for chromatin
  • chromatin beads on a string pack into each other to make nucleosomes (interphase)
  • packs into chromosome in extended form
  • this condenses into a section of chromosome
  • this condenses into spot on centromere
24
Q

what are 3 ways that make chromatin dynamic

A
  • protein assemblies (chromatin remodeling complexes)
  • histone tail modifications
  • histone (de)acetylation
25
Q

describe histone acetylation

A
  • acetyl group added to positive amino acids in histone tails
  • the charge neutralizes and prevents binding to neighboring nucleosomes
  • relaxation of chromatin structure to activate transcription
26
Q

describe histone deacetylation

A
  • acetyl group is removed from histone tails
  • becomes charged and allows for binding to neighboring nucleosomes
  • chromatin structure condenses and transcription is inhibited
27
Q

define telomere

A

repeated DNA sequence on ends of chromosomes which allows for them to be replicated and protection

28
Q

define replication origin

A

where the replication of the chromosome begins

29
Q

define centromere

A

DNA sequence that allows attachment to mitotic spindles

30
Q

how are DNA strands read

A

from 5’ to 3’ ends

BIOL 2030 (16 decks)

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