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Biology > DNA, cell cycle, cell reproduction, mitosis and meiosis > Flashcards

DNA, cell cycle, cell reproduction, mitosis and meiosis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Where is DNA found?

A

In the nucleus and mitochondria of eukaryotic cell

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2
Q

What is the structure of DNA?

A

Linear polynucleotide consisting of 4 types of monomeric nucleotides. IS a double helix

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3
Q

What are the 3 parts that each nucleotide consists of?

A

A deoxyribose sugar (5 carbon hydrophillic), a phosphate group (hydrophilic) and a nitrogenous base (hydrophobic)

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4
Q

What are the 4 nitrogenous bases?

A

Adenine, Cytosine, Guanine and Thymine

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5
Q

What does adenine and guanine have in common?

A

Both are purines which are double ringed structures

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6
Q

What does cytosine and thymine have in common?

A

Both are pyrimidines which are single ringed structures

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7
Q

What nitrogenous bases match together?

A

Thymine and Adenine , Cytosine and Guanine

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8
Q

What is the order from outside to in of the nucleotide?

A

Phosphate, Sugar then the base

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9
Q

What are Chargaff’s Rules?

A
  1. The amount of 1 base always approx equals the amount of a particular second base
  2. The relative amounts of A, T, G, C vary per species
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10
Q

What is the directionality of DNA?

A

5’ to 3’

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11
Q

What is the semiconservative model?

A

2 strands of the parental molecule separate and each functions as a template for synthesis of a new, complementary strand

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12
Q

What are the 3 steps of DNA replication?

A

Initiation, Elongation and Termination

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13
Q

What occurs in the initiation phase of DNA replication?

A

Helicase unwinds and separates DNA strand forming a replication fork by breaking hydrogen bonds. Single strand binding proteins keep strands from reattaching. Topoisomerase breaks, swivels and rejoins DNA strand due to untwisting of helix. DNA replication specific to topoisomerase-DNA gyrase. RNA primer makes start point for DNA polymerase to attach nucleotides, RNA primer made by primase

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14
Q

What occurs in the elongation phase of DNA replication?

A

DNA polymerase continues matching nucleotides to RNA primer chain. Reads DNA template from 3’ to 5’. New strand synthesized from 5’ to 3’. Eukaryotes have 11 different polymerases. Has both a leading strand and a lagging strand.

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15
Q

What occurs at the leading strand in elongation in DNA replication?

A

Only 1 primer needed for polymerase to start adding nucleotides. Moves towards replication fork

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16
Q

What occurs at the lagging strand in elongation in DNA replication?

A

Multiple primers needed. Moves away from replication fork. Polymerase III creates Okazaki fragments. Enough template must be exposed before polymerase can add nucleotides. Polymerase I takes off RNA primer through 5’ to 3’ exonuclease and adds nucleotides in its place. DNA ligase joins all Okazaki fragments after polymerase I has finished

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17
Q

What occurs in the termination phase of DNA replication?

A

Does not replicate to the end. Telomers absorb loss. Stops at termination site sequence in DNA or a protein attaching to this stop site to physically stop replication

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18
Q

How to form chromosome shape from DNA?

A

DNA is divided into multiple DNA molecules, Topoisomerases coil DNA molecules. Histones wrap this DNA into nucleosomes. Further into chromatins then chromosomes

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19
Q

What does the cell continuously cycle through?

A

Replication (synthesis), growth, mitosis and growth

20
Q

What is interphase and mitotic phase?

A

Interphase is a general term for most of the cycle. Mitotic phase is prophase, metaphase, anaphase and telophase

21
Q

What happens during synthesis stage?

A

Each chromosome is replicated

22
Q

What occurs in the prophase of mitosis?

A

Chromosome starts to condense, nuclear envelope starts to break down, organelles break up and move to sides and mitotic spindle begins to form from opposite poles

23
Q

What occurs in the prometaphase of mitosis?

A

Nuclear envelope breaks down fully, chromosomes fully condense, mitotic spindle grows and organises chromosomes and kinetochore connect chromosomes to spindle

24
Q

What occurs in the metaphase of mitosis?

A

Mitotic spindle aligns chromosomes along centre, sister chromatids still attached

25
Q

What occurs in anaphase of mitosis?

A

Sister chromatids separated at centromere and pilled to edge of cell

26
Q

What occurs in telophase?

A

Spindle dissapears, mew nuclear envelope forms, decondense to chromatids

27
Q

What is cytokinesis?

A

The actual separation of the cells

28
Q

Why is meiosis necessary?

A

For sexual reproduction and occurs in sex cells to produce sperm and egg cells. 2 nuclear divisions but only a single replication. Produces haploid gametes and is the key source of genetic variation between individuals. Produces new combinations of genes by recombination and independent assortment

29
Q

What are the main differences between mitosis and meiosis?

A

Mitosis- 2 daughter cells, genetically identical, diploid and 1 cell division
Meiosis- 4 daughter cells, nonidentical, haploid and 2 cell divisions

30
Q

What did Mendel find through pea experiments?

A

Introduced the idea of heritable traits or ‘genes’ and what we know as dominant and recessive traits. Mendel noted that there are alternative forms of genes called alleles that are at a specific point of locus on a chromosome

31
Q

Define Dominant

A

allele variant masking or overriding the effect of the other allele variant. Represented by a capital letter

32
Q

Define recessive

A

Allele variant masked or overridden by the effect of the dominant allele variant. Represented by lower case letters

33
Q

Define genotype

A

Set of alleles that an individual has directing the physical appearance of a trait

34
Q

Define phenotype

A

Physical appearance of a trait

35
Q

What is the law of segregation?

A

The 2 alleles for a heritable character segregate (separate from eachother) during gamete formation and end up in different gametes (meiosis)

36
Q

What is the law of independent assortment?

A

2 or more genes assort independently-each pair of alleles segregates independently of eachother pair of alleles during gamete formation

37
Q

What is pedigree analysis and its symbols?

A

A family tree that describes the interrelationships or parents and children across generations. Blank square is male, blank circle is female. If filled in it means affected

38
Q

What are recessively inherited disorders?

A

Only shows in homozygous individuals eg cystic fibrosis. Heterozygous are carriers but does not show

39
Q

What are sex linked genes?

A

If it sits on x or y chromosomes is linked. A recessive x-linked trait you need 2x copies in females and only 1 x copy in male (hemizygous)

40
Q

What is the Hardy Weinberg equilibrium?

A

A populations allele and genotype frequencies will remain constant in the absence of evolutionary mechanisms (no evolution). Assumptions are no mutation, random mating, no gene flow, infinite population size and no selection

41
Q

What are the equations for frequency of alleles and frequency of genotypes?

A

P + Q =1 where p is dominant frequency and q is recessive frequency
P2 +2PQ +Q2 = 1 where p2 is homozygoys dominant, 2pq is heterozygous and q2 is homozygous recessive

42
Q

How many genes encode for proteins in humans?

A

30-40 K

43
Q

What are noncoding genes called and where are they located?

A

Called introns and they are the gaps inbetween genes and highly repeated regions

44
Q

What are noncoding genes used for?

A

Have a higher degree of variation between individuals because a mutation will not affect the appearance of functioning of the individual. Most of the variation are sequence polymorphisms or length polymorphisms

45
Q

What are single nucleotide polymorphisms (SNP)?

A

Single base change and are the basis of most of the variation we see in individuals.

46
Q

What are Simple tandem repeats (STR)?

A

Length polymorphisms. Most forensic NDA profiling uses STR analysis

Biology (19 decks)

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