3.2 Chromosomes Flashcards

1
Q

chromosomes of prokaryotic cells

A
  • singular chromosome = only one copy of each gene
  • coiled up in nucleoid region
  • genes are needed for basic life processes
  • chromosome is makes, no histones
  • second copy is made before binary fission
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2
Q

plasmids in prokaryote bacteria

A

small extra DNA molecules
- small, circular, naked
- few genes that are not essential for cell function but might be helpful (eg. antibiotic resistance)
- not replicated at the same time as chromosome (cell can have many copies)
- can be transferred between prokaryotic cells

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3
Q

plasmids are also used…

A

by scientists to artificially transfer genes between species

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4
Q

audioradiography

A
  • grown with thymine nucleotides with radioactive hydrogen isotope
  • e. coli cells placed on dialysis membrane and lysed with enzymes
  • cell contents applied to photgraphic emulsion palced in dark
  • radioactive isotopes reacted with emultion making dark areas
  • dark areas= presence of DNA
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5
Q

conclusion of cairn’s technique

A
  • e.coli has single cirular chromosome
  • provided evidence for semi conservative replication
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6
Q

eukaryotic chromosomes

A
  • linear strands of dna in helix
  • nucleosomes formed by wrapping dna around histones
  • coiled into chromatin during interphsse
  • supercoiled to form characteristic chromosome shape in mitosis
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7
Q

Eukaryotic cells possess…

A

multiple chromosomes with different genes

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8
Q

each chromosome carries….

A

a different set of genes in a specific order

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9
Q

chromosomes can vary by

A
  • length (number of base pairs in dna molecule)
  • position of the centromere
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10
Q

all individuals of a species…

A

have same chromosomes with same gene/locus

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11
Q

genome:

A

complete set of genetic info in organism

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12
Q

genomic size:

A

vary among organisms

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13
Q

proportion of DNA

A

that acts as functional genes is variable

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14
Q

homologous chromosomes

A
  • same size and structure, same sequence of genes, may have different alleles for genes
  • to interbreed two organisms must have homologous chromosome sets
  • each chromosome type comes from the egg and otehr comes from the sperm to make homogolous pairs
  • unless motehr gives x and father gives y (not homogolous)
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15
Q

diploids

A
  • 2 homologous pairs
  • 2 copies of each gene
  • 46 chromosome in human
  • somatic cell
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16
Q

haploids

A
  • 1 chromosome
  • 1 copy of each gene
  • 23 chromosome in human
  • gamete/sex cell
17
Q

sexual reproduction

A

haploid sperm and egg cells fuse into fertilization to produce a diploid zygote, which divides in mitosis to form embryo

18
Q

chromosome number is…

A

fundemental characteristic that defines a species

19
Q

organisms with different numbers of chromosomes are…

A

unlikely to be able to interbreed successfully

20
Q

chromosome number does not equal

A

complexity

21
Q

number of chromosomes in a species is known as the

22
Q

chromosome number tends to be…

A

conserved across millions of years of evolution

23
Q

in rare cases, chromosomes can…

A

fuse or split during evolution to change the chromosome number of species

24
Q

sex determination

A

XX - female
XY- male

25
x chromosome
- large with centromeme in the center - x carries many genes in non-homologous region that is not in Y chromosome
26
y chromosome
small with a centromere near the top - SRY gene on Y leads to male development
27
eggs
produced by females and have XX chromosomes
28
sperms
produced by males and have XY chromosomes
29
karyogram
diagram or photgraph of the chromosomes present in a nucleus of eukaryote cell arranged in homologous pais of decreasing length
30
karyotype
property of the cell described by number and tyoe of chromosomes in nucleus
31
3 key features to identify chromosomes
- seen in metphase most clearly - stains give chromosome distinctive banding pattrn - micrograph arranges in size and bandin pattern
32
trisomy
having a third (extra) copy of a chromosome
33
monosomy
having only one (missing) copy of a chromosome