Biology 10th ICSE: Structure of Chromosomes Cell cycle and cell division Flashcards

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1
Q

What are chromosomes?

A

They are highly coiled and condensed chromatin fibres

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2
Q

Who studied chromosomes in animals for the first time? (hint: ‘walt___ ________’)

A

German Scientist Walther Flemming | 1882

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3
Q

A single DNA molecule is very large and thus described as a ______.

A

Macromolecule

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4
Q

What forms the ‘rungs’ of the ladder-like arrangement of the DNA?

A

Nitrogenous Bases

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5
Q

What is DNA strand composed of?

A

Repeating Nucleotides; composed of

  • phosphate
  • sugar (pentose)
  • a nitrogenous base
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6
Q

Name 4 nitrogenous bases found in DNA

A

a) Adenine
b) Guanine
c) Cytosine
d) Thymine

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7
Q

Describe the appearance of chromatin under an electron microscope

A

long, thin, darkly stained fibre

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8
Q

What are the proteins that help in the coiling and packaging of DNA into structural units called ‘nucleosomes’

A

Histones

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9
Q

Histones are the proteins that help in the coiling and packaging of DNA into structural units called _______.

A

nucleosomes

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10
Q

What does the DNA strand wind around?

A

8 histone proteins called ‘The Histones Octamer’.

Combined with DNA, each complex is called a nucleosome

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11
Q

What are Genes?

A

They are specific sequences of nucleotides on a chromosome that encode proteins, which then express in the form of some particular feature of the body

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12
Q

State 4 needs for new cells

A
  • Growth
  • Replacement
  • Repair
  • Reproduction
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13
Q

What is the cell cycle?

A

The Cell Cycle is a series of events that take place in a cell leading to duplication of its DNA and subsequent division of the cell to produce 2 daughter cells.

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14
Q

name the phases of Interphase

A
  • First Growth Phase G1
  • Synthesis Phase S
  • Second Growth Phase G2
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15
Q

Can the cell cycle go on endlessly?

A

No dumbass 🙄

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16
Q

Cell Division leading to production of diploid cells for growth

A

Mitosis

17
Q

What is Meiosis?

A

Cell Division leading to production of haploid cells or gametes

18
Q

During Prophase each centriole is surrounded by radiating rays termed _____.

A

Aster

19
Q

Which of these don’t happen in Prophase?

a) fibres called ‘spindle fibres’ appear between 2 daughter centrioles called ‘spindle fibres’
b) nuclear membrane disappears
c) Centrioles start moving apart to opposite poles
d) chromosomes start moving towards equator of cell

A

c) Centrioles start moving apart to opposite poles

20
Q

Which of these happens in Metaphase?

a) fibres called ‘spindle fibres’ appear between 2 daughter centrioles called ‘spindle fibres’
b) nuclear membrane disappears
c) Centrioles start moving apart to opposite poles
d) chromosomes start moving towards equator of cell

A

c) Centrioles start moving apart to opposite poles

21
Q

Are asters formed in plant or animal cell?

A

Asters are formed in Animal Cells