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Science 2019 > Biology > Flashcards

Biology Flashcards

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Biology 101 flashcards
1
Q

What is the structure of DNA?

A

A twisted double helix made up of chains of nucleotides, which are joined by hydrogen bonds between the pentose sugar of one nucleotide and the phosphate of another nucleotide. Complimentary nucleotides are joined with the base pairs.

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2
Q

What are the nitrogenous bases and their pairing?

A

Adenine - Thymine

Cytosine - Guanine

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3
Q

Where is DNA located?

A

DNA is located in the nucleus of most organisms.

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4
Q

Where is DNA located in bacteria?

A

Since bacteria don’t have nuclei, their DNA is free-floating in the cytoplasm.

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5
Q

What does DNA stand for?

A

DeoxyriboNucleic Acid

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6
Q

How does DNA replicate itself?

A
  • 2 complementary strands of DNA have to be seperated by the enzyme helicase.
  • free floating DNA nucleotides in the cytoplasm bind complimentarily to the exposed template DNA strands, with the help of the enzyme polymerase.
  • as the two double strands are being produced, they begin to twist back into the double helix shape.
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7
Q

What is mitosis? State the process.

A

Mitosis is the process that most cells use to divide. A single cell divides into two daughter cells which carry the same number of chromosomes and the same genetic code as the parent. Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.

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8
Q

What is meiosis? State the process.

A

A special type of cell division used only for the production of sperm or egg cells. Interphase, prophase 1, metaphase 1, anaphase 1, telophase 1, cytokinesis, prophase 2, metaphase 2, anaphase 2, telophase 2, cytokinesis.

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9
Q

Why is it important that during mitosis the daughter cells end up with the same number of chromosomes as the parent cell?

A

The daughter cells must be identical to the parent cells, meaning that they also carry the same number of chromosomes. Otherwise they would have a different amount of genetic information.

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10
Q

How does crossing over in meiosis create variation?

A

When the chromosomes cross over, they create non-identical chromatids in meiosis II chromosomes, and results in all daughter cells being different (variation).

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11
Q

What is the difference between sexual and asexual reproduction?

A
  • sexual involves 2 parents; asexual involves 1 parent

- Asexual all offspring are genetically identical whereas sexual has variation

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12
Q

What are the differences between meiosis and mitosis?

A
  • mitosis produces identical cells, whereas meiosis produces a variety of haploid cells.
  • all cells can undergo mitosis, whereas only sex cells can undergo meiosis.
  • stemming from one parent cell: mitosis produces 2 daughter cells, meiosis produces 4.
  • In mitosis, daughter cells have the same number of chromosomes as the parent cell, whereas in meiosis daughter cells have half the number of chromosomes as the parent cell.
  • mitosis undergoes 1 cell division, meiosis undergoes 2 cell divisions.
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13
Q

What are the advantages and disadvantages of sexual and asexual reproduction?

A

.Asexual reproduction:
-Advantages: fast; only one parent needed.
-Disadvantages: little variation; harder for adaption to occur, easily affected by disease or environmental change.
Sexual reproduction:
-Advantages: removes harmful mutations from the population; variation (increases chance of survival); unique individuals
-Disadvantages: two organisms are requires (have to search for mates); reproduction rate is slower; more energy is required; fewer offspring are produced.

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14
Q

Define homozygous.

A

Having two identical alleles on homologous chromosomes.

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15
Q

Define heterozygous.

A

Having two different alleles on homologous chromosomes.

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16
Q

Define genotype.

A

Genetic information carried by an individual.

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17
Q

Define phenotype.

A

The set of observable characteristics of an organism - appearance and behaviour.

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18
Q

Define autosomal inheritance.

A

When a trait is passed down through the autosomes (chromosomes 1-22).

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19
Q

Define sex-linked.

A

When a trait is passed down through the sex chromosomes (chromosome 23).

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20
Q

Define dominant.

A

Allele which masks the effect of a recessive allele, and is expressed in the organism’s phenotype.

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21
Q

Define recessive.

A

The trait that remains hidden in the heterozygous condition (masked by the dominant trait), and seen only in the homozygous condition.

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22
Q

What is codominance?

A

When both alleles in a heterozygous offspring are expressed in the phenotype.

23
Q

What is incomplete dominance?

A

When genes have equal dominance and the characteristics blend or combine to give an intermediate characteristic.

24
Q

What is an allele?

A

Alternate forms of the same gene.

25
Q

What is the parent generation?

A

The first set of parents.

26
Q

What is the F1 generation?

A

Offspring of the first parents.

27
Q

What is the F2 generation?

A

Offspring of the offspring of the first parents (granddaughters if you will)

28
Q

What is mutation?

A

A mistake that happens as DNA is copied, causing a change in the base sequence. It can change how an organism looks, how it behaves, and its physiology.

29
Q

What are the possible sources of mutation?

A
  • inherited
  • mistakes when DNA is copied
  • environmental damage
  • —- carcinogens, high temperatures, radiation, etc.
  • missing or extra chromosomes
30
Q

What are the importance of mutations in providing genetic variation?

A

It can create entirely new alleles in a population.

31
Q

How are genetic disorders caused?

A

An altered gene or set of genes.

32
Q

What is a homologous pair of chromosomes?

A

chromosomes that share the same structural features, and the same genes at the same loci positions.

33
Q

How are chromosomes arranged in karyotypes?

A

Due to shape, size, bands, etc.

34
Q

Define a nucleotide and label its parts.

A

The building blocks of DNA comprised of deoxyribose (pentose) sugar, a phosphate group, and a nitrogenous base, all held together by nitrogen bonds.

35
Q

Define haploid.

A

One copy of genetic material subdivided into chromosomes; non homologous chromosomes.

36
Q

Define diploid.

A

Two copies of genetic material subdivided into chromosomes; pairs of homologous chromosomes.

37
Q

What is a gene?

A

A sequence of DNA on a chromosome that codes for a particular protein.

38
Q

What are some examples of asexual reproduction? Explain them.

A
  • Budding: a new organism develops from an outgrowth or bud due to cell division at a particular site.
  • Fission: a new organism is made from the original organism splitting, and regrowing from that piece.
39
Q

Why is cell division important?

A

For growth, repair, and reproduction.

40
Q

What happens in interphase (mitosis + meiosis)?

A

Chromosomes begin to be replicated

41
Q

What happens in prophase (mitosis)?

A

single chromosomes have replicated; chromosomes condense and become visible; nuclear membrane breaks down

42
Q

What happens in metaphase (mitosis)?

A

chromosomes line up along the equator of the cell.

43
Q

What happens in anaphase (mitosis)?

A

chromosomes are pulled apart and individual chromatids move to opposite ends of the cell.

44
Q

What happens in telophase (mitosis)?

A

nuclear membranes appear around each set of chromosomes; spindle fibres disappear; chromosomes decondense.

45
Q

What happens in cytokinesis (mitosis + meiosis)?

A

the parent cell divides to produce two daughter cells.

46
Q

What happens in prophase I (meiosis)?

A
  • chromosomes have replicated
  • some sections of chromosomes may cross over/swap (chiasmata)
  • nuclear membrane breaks down
  • spindle fibres form.
47
Q

What happens in metaphase I (meiosis)?

A

Homologous chromosomes from each parent pair up randomly.

48
Q

What happens in anaphase I (meiosis)?

A

Whole chromosomes are pulled to the opposite end of the cell.

49
Q

What happens in telophase I (meiosis)?

A

Nuclear membranes appear around each set of chromosomes.

50
Q

What happens in prophase II (meiosis)?

A
  • nuclear membrane starts to break down
  • spindle fibres form
  • chromosomes condense
51
Q

What happens in metaphase II (meiosis)?

A

Chromosomes line up at the equator of the cell.

52
Q

What happens in anaphase II (meiosis)?

A

chromosomes are pulled apart and individual chromatids move to the opposite ends of the cell.

53
Q

What happens in telophase II (meiosis)?

A
  • nuclear membranes appear around each set of chromosomes.

- chromosomes decondense.

54
Q

What can karyotyping do?

A

Count the number of chromosomes, and look for structural changes in chromosomes. Essentially this can detect any mutations and disorders.

Science 2019 (4 decks)

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