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Science > SBI3U Test #1 > Flashcards

SBI3U Test #1 Flashcards

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Biology 101 flashcards
1
Q

What are the 3 parts to a nucleotide?

A

A phosphate group, deoxyribose sugar, and a nitrogenous base.

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2
Q

What are the four types of nitrogenous bases?

A

Adenine, cytosine, thymine, and guanine.

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3
Q

What nitrogenous base is paired with cytosine?

A

Guanine.

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4
Q

What nitrogenous base is paired with adenine?

A

Thymine.

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5
Q

What is a nitrogenous base?

A

It is part of the “rungs of the ladder” in DNA. These include adenine, guanine, cytosine, and thymine. Each contain nitrogen.

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6
Q

What is a gene?

A

Genes are part of the chromosomes and are made of DNA. They control how certain traits are expressed in a cell and can be passed down to offspring. They determine things like hair colour or blood type.

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7
Q

What is a genome?

A

A genome contains all 46 chromosomes and has all the inheritable traits of the organism in it.

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8
Q

What is a chromosome?

A

It is a structure within the nucleus of the cell containing all the cell’s genetic information.

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9
Q

What are nucleosomes?

A

Nucleosomes are the units created by a strand of DNA coiled twice around histones.

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10
Q

What are chromatin?

A

They are nucleosomes that have been coiled into compact fibres.

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11
Q

Name 4 reasons why cells divide.

A
  1. To maintain an adequate surface area to volume ratio. Not having sufficient surface area means that wastes will accumulate and not enough needed materials (like glucose) will get into the cell.
  2. To increase the size of the organism
  3. To repair and replace damaged cells and tissues.
  4. In order to become specialized cells from stem cells.
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12
Q

What is a nuclear membrane?

A

It is a membrane around the nucleus that controls what goes in and out of the cell, and keeps the contents of the nucleus inside.

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13
Q

What is the nucleolus?

A

It is the part of the nucleus that makes ribosomes. (Ribosomes are used to make proteins)

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14
Q

What are centrioles?

A

As a pair, centrioles are called the centrosome. They construct the micro-tubules that become spindle fibres.

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15
Q

What are chromatin?

A

Chromatin are DNA in its decompacted (unwound) state.

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16
Q

What are the sister chromatids?

A

They are duplicate copies of chromatid held together by the centromere to form a chromosome as a whole.

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17
Q

What are spindle fibres?

A

Spindle fibres are of micro-tubules by the centrioles. They are used to line up the chromosomes along the equatorial plate and pull them apart at the centromeres. (Like the fishing line if the centriole was the fisherman and the centromere was the fish.)

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18
Q

What are micro-tubules?

A

They are the material used to make up spindle fibres.

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19
Q

What are chromosomes?

A

They are compacted DNA.

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20
Q

What is the aster?

A

The aster is the centriole with spindle fibres forming out of it. (looks like a spider or an aster flower)

21
Q

What is the equatorial plate?

A

The equatorial plate is the imaginary line across the cell that the sister chromatid line up on in during metaphase.

22
Q

What are the 3 stages of DNA replication?

A
  1. Helicase unzips the parent strand by breaking the hydrogen bonds between the base pairs
  2. Enzymes help free-floating nucleotides bond following pairing rules
  3. Enzymes reattach the backbone of deoxyribose sugars and phosphates.
23
Q

What are 2 causes of mutations?

A

Spontaneous and Mutagens

24
Q

How and why to spontaneous mutations occur?

A

They occur under natural condition due to miss-pairing in DNA replication, nondisjunction (chromosome pairs do not separate properly during cell division)

25
Q

What are mutagens? What do they result in?

A

They are agents that increase risk of mutations occuring. They result in increase in the frequency of mutations and change the chemical structure.

26
Q

List some known mutagens. (at least 5)

A
  • LSD (acid drug)
  • Mustard gas
  • U-V light
  • X-rays
  • Chemicals in cigarette smoke
  • Nuclear radiation
27
Q

What are some suspected mutages? (name at least 2)

A

Prolonged exposure to strong electric and electromagnetic fields, agent orange (used in herbicidal warfare in the Vietnam war)

28
Q

What are two ways that DNA changes (these changes cause genetic disorders)?

A

Errors in DNA replication and errors in cell division (mitosis or meiosis).

29
Q

What do errors in DNA replication in body cells (somatic cells) result in?

A

The cell will die or cancer will occur.

30
Q

What is the result of DNA replication errors in sex cells?

A

Only non-lethal mutations will be pased on to next generation, otherwise the sex cell will die.

31
Q

Why are DNA replication errors rare?

A

Enzymes triple check the replication code.

32
Q

What do errors in cell division result in?

A

Usually result in large changes in the chromosomes: potentially large regions or entire chromosomes missing (monosomy) or extra chromosomes (trisomy).

33
Q

What do cells read instructions from DNA for?

A

For the creation of proteins required to perform cell functions

34
Q

Why are cells required to replicate?

A

They replicate to support growth, repair damage and maintain large surface area to volume ratios.

35
Q

What are gametes required for?

A

The sexual reproduction of an organism.

36
Q

What must happen before either mitosis or meiosis can occur to reproduce cells?

A

DNA replication.

37
Q

Where in the cell is DNA kept and why?

A

DNA is kept in the nucleus of the cell because it is a fragile molecule and requires protection.

38
Q

Who used X-ray diffraction to help determine the structure of DNA?

A

Rosalind Franklin

39
Q

What is the structure/shape of DNA usually described as?

A

The double helix.

40
Q

What is the human genome?

A

The complete set of instructions contained within the DNA of person.

41
Q

Why can DNA fingerprinting be used to identify criminals?

A

Because each individual’s DNA is different, with the exception of identical twins.

42
Q

Who was awarded the Nobel Prize for the discovery of the DNA double helix?

A

Watson and Crick.

43
Q

What is DNA composed of?

A

Repeating nucleotides.

44
Q

How many hydrogen bonds are used to bond adenine and thymine?

A

Two.

45
Q

How many hydrogen bonds are used to bond guanine and cytosine?

A

Three.

46
Q

State 2 functions of DNA.

A
  1. Carrying genetic infornation down to offspring.
  2. Providing the code for the cell to make proteins required to carry out various cell functions.
47
Q

Why is DNA a unique molecule compared to fats, carbohydrates, and proteins?

A

DNA is unique because it is the only molecule our bodies provide for ourselves by self-replicating.

48
Q

Given the rule of complementary base pairing, it is reasonable to expect upon analysis of DNA that the amount of:

a. guanine = adenine
b. guanine = thymine
c. adenine + thymine = guanine + cytosine
d. adenine + guanine = cytosine + thymine
e. adenine + thymine = guanine + thymine

A

d. adenine + guanine = cytosine + thymine

49
Q

What are nucleotides made up of?

A

A deoxyribose, a phosphate, a nitrogen base.

Science (20 decks)

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