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mod 5: heredity > INQUIRY Q2 > Flashcards

INQUIRY Q2 Flashcards

1
Q

DNA

A

Stands for Deoxyribose Nucleic Acid, a molecule composed of two strands that coil around each other to form a double helix carrying genetic instructions.

  • Essential for the development, functioning, growth and reproduction of all known organisms and many viruses.
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2
Q

Chromatin

A

The general packaging of DNA around histone proteins, decondensed as a long thin string.

For most of the cell cycle, DNA is packaged in the form of chromatin.

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3
Q

Chromosomes

A

An additional level of organisation of chromatin that occurs during mitosis and meiosis.

  • Located inside the nucleus of animal and plant cells
  • Contains genes which has code for proteins
  • Exist in duplicated or unduplicated states
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4
Q

Autosomal Chromosomes

A

No. 1 - 22 chromosomes are the pair of chromosomes that regulate the somatic characteristics.

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5
Q

Sex Chromosome

A

No. 23 chromosomes are the pair of chromosomes that regulate the sex-linked traits.

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6
Q

Cell Cycle

A

A series of events that takes place in a cell as it grows and divides.

A cell spends most of its time in interphase and prepares for cell division by replicating its chromosomes (genetic material).
* The cell cycle is a 4 stage process, consisting of G1, Synthesis, G2 and Mitosis (or Meiosis).

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7
Q

Cell cycle:

Gap 1 (G1)

A

The period in the cell cycle after cell division and before the start of DNA replication.
* Cells grow and monitor their environment to determine whether another round of cell division can be intiated.

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8
Q

Cell cycle:

Synthesis

A

The period in the cell cycle of DNA synthesis.
* Cells replicate their chromosomes.

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9
Q

Cell cycle:

Gap 2 (G2)

A

The period in the cell cycle between the end of DNA replication and start of cell division.
* Cells check DNA replication has sucessfully completed and make any necessary repairs.

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10
Q

Allele

A
  • Each of two or more alternative forms of a gene that are found at the same place on a chromosome.
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11
Q

Chromatid

A
  • One of two genetically identical halves of a replicated chromosome.

After DNA replication, a chromosome consists of two identical structures called sister chromatids, which are joined at the centromere.

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12
Q

Sister Chromatid

A

One of two chromatids of the same chromosome joined together by a common centromere.

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13
Q

Non-sister Chromatid

A

One of the two chromatids of paired homologous chromosomes, the pairing of a paternal chromosome and a maternal chromosome.

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14
Q

Genes

A

A distinct sequence of nucleotides on a chromosome which code for some characteristic which is transferred from parent to offspring.

Dominant and recessive alleles: An allele of a gene is said to be dominant when it effectively overrules the other (recessive allele).

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15
Q

Mitosis

A

The process of nuclear division in which a single parent cell divides once to produce two genetically identical daughter cells.

Main purpose of mitosis is to accommodate grotwth of the organism and to replace damaged cells.

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16
Q

Mitosis:

Interphase

A
  • Nuclear DNA remains in a semi-condensed chromatin configuration.
  • DNA is replicated and results in the formation of sister chromatids, an identical pair of DNA molecules, that are firmly attached to the centromeric region.
  • Centrosomes replicate and move to opposite ends of the cell’s pole.
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17
Q

Mitosis:

Prophase

A
  • Chromatin condenses into chromosomes and becomes visible under a microscope.
  • Miotic spindle fibres start to form from microtubules within the centroles.
  • Nuclear membrane dissolves to allow spindle fibres to attach to chromosomes.
  • Spindle fibre attaches to the area of centromere on eah sister chromatid.
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18
Q

Mitosis:

Metaphase

A
  • Centosomes are at the opposite end of the cell’s pole.
  • Spindle fibres attach to the centromere of each pair of sister chromatids.
  • Sister chromatids line up at the equator of the cell.
  • Spindle fibres ensure that sister chromatids will seperate and go to different daughter cells when the cell divides.
19
Q

Mitosis:

Anaphase

A
  • Sister chromatids are pulled to opposite ends of the cell by the shortening of the spindle fibres.
  • At the end of anaphase, each pole has a full set of chromosomes.
20
Q

Mitosis:

Cytokinesis

A
  • Division of the cytoplasm to form two new cells each with their own cell membrane.
  • Cytoplasm splits equally between the two cells.
  • Chromosomes unravel to become chromatin.
21
Q

Meiosis

A

The process where a single parent cell divides twice to produce genetically different four daughter cells containing half the amount of orignal genetic information.

  • Resulting cells are sex gametes.
22
Q

Homologous Chromosomes

A

A pair of chromosomes that consists of one maternal and one paternal chromosome that are the same length and carry genes at the same locations.

23
Q

Meiosis I:

Interphase

A
  • DNA in the cell is copied resulting in two identical full sets of chromosomes.
  • Two centrosomes are located outside of the nucleus in the cell.
  • During interphase, microtubules extend from these centrosomes.
24
Q

Meiosis I:

Prophase I

A
  • Replicated chromosomes condense into X-shaped structures.
  • Chromosomes organise in homologous pairs so that both copies of chromsomes form together as a tetrad.
  • Any pairs of chromatid arms overlap at a point of contact (chiasma), causing them to break and recombine to produce new combinations of genes, known as “crossing over”.
  • At the end of Prophase I, the nuclear membrane dissolves away.
25
Q

Meiosis I:

Metaphase I

A
  • Homologous pairs of chromosomes line up on the equator randomly, known as a concpet called Independent Assortment.
  • Centrioles are now at opposite poles of the cell with the metotic spindles extending from them.
  • Meiotic spindle fibres attach to one chromosome of each homologous pair.
26
Q

Meiosis I:

Anaphase I

A
  • Homologous pairs of chromosomes are then pulled apart by the meiotic spindle, with one homologous chromosome to one pole of the cell and the other to the opposite pole.
  • Sister chromatids stay attached at their centromeres.
27
Q

Meiosis I:

Telophase I

A
  • Chromsomes complete their move to the opposite poles of the cell.
  • At each pole of the cell, a full set of chromosomes gather together.
  • A new membrane forms around each set of chromosomes to create two new nuclei.
28
Q

Meiosis I:

Cytokinesis

A
  • Single cell then pinches in the middle to form two separate daughter cells each, containing a full set of chromosomes within a nucleus.
29
Q

Meiosis II:

Prophase II

A
  • There is now two genetically different daughter cells each with n chromosomes.
  • Each chromosome has two chromatids.
  • Membrane around the nucleus in each daughter cell dissolves away releasing the chromosomes.
  • Spindles form again.
30
Q

Meiosis II:

Metaphase II

A
  • In each of the two daughter cells, the chromosomes line up along the equator.
  • Meiotic spindles fibres at each pole of the cell attach to each of the sister chromatids.
31
Q

Meiosis II:

Anaphase II

A
  • Sister chromatids are then pulled apart to opposites poles due to the action of the meiotic spindle.
  • Separated chromatids are now individual chromosomes consisting of only one chromatid.
32
Q

Meisosis II:

Telophase II

A
  • Chromosomes complete their move to the opposite poles of the cell
33
Q

Meisosis II:

Cytokinesis II

A
  • Membrane forms around each set of chromosomes to create two new cell nuclei.
34
Q

Structure of DNA

A

A double helix, a large molecule made up of a long chain of nucleotides.

35
Q

Structure of Nucleotides

A
  • Deoxyribose
  • -PO4 (Phosphate group)
  • Nitrogenous Base
36
Q

Nitogenous bases

A

The four nitrogenous bases: Adenine, Thymine, Guanine and Cytosine (AT and GC are paired together).

The bases are divided by two groups:
* Purine Bases: consisting of two rings (A & G)
* Pyrimidine: consisting of one ring, (C & T)

37
Q

Deoxyribose (sugar) Structure

A

Made of four carbon atoms and one oxygen atom.

38
Q

Hydrogen Bonds in DNA

A
  • Two hydrogen bonds between A and T
  • Three hydrogen bonds between G and C
  • Convalent bonds between the sugar and phosphate groups
39
Q

Enzymes in DNA replication:

Helicase

A

Helicase unwinds and separates the 2 DNA strands into a replication fork by breaking the hydrogen bonds between the nitrogenous bases (A, T, G, C).

40
Q

Enzymes in DNA replication:

Binding Proteins

A

Binding proteins attach to the 2 DNA strands to keep them separated and twisted.

41
Q

Enzymes in DNA replication:

Topoisomerase

A

Topoisomerase attaches ahead of the fork to relieve stress caused by unzipping on the DNA molecule and prevents it from coiling so it can continue to separate.

42
Q

Enzymes in DNA replication:

RNA primers

A

RNA primers serves as a start site for DNA polymerase when DNA needs to be copied

43
Q

Enzymes in DNA replication:

DNA polymerase

A

DNA polymerase adds new nucleotides and creates the new strand in the 5’ and 3’ direction.

mod 5: heredity (3 decks)

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