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Biology 101 > Exam 1 (Genetics) > Flashcards

Exam 1 (Genetics) Flashcards

1
Q

What are genetics?

A
  • the study of the process by which information is transmitted from one generation of living things to the next.
  • Every living thing is organized via coded information, called its genetic material
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2
Q

What does reproduction involve?

A

duplication and transmission of an organisms genetic material.

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3
Q

What is a gene?

A
  • an information entity. DNA that codes for a single genetic instruction
  • The effects of every gene depend both upon other genes, and upon the environment.
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4
Q

What is an allele?

A

An allele is ONE variant of a gene.

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5
Q

What happens when there is substitutions in the 3rd codon?

A
  • no change at all, they code for the same transfer RNA = same protein is produced.
  • Other substitutions produce profound effects, sickle cell anemia is caused by a single nucleotide substitution: GAG—> GUG changes normal hemoglobin to hemoglobin that “sickles” under low oxygen concentrations.
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6
Q

what is a prokaryote?

A
  • the simplest, oldest, and most common organisms on the planet.
  • include archaea and bacteria
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7
Q

Prokaryotic characteristics?

A
  • smaller genome than a typical eukaryote.
  • its a simple loop of DNA, attached to the cell membrane.
  • is a lot of DNA in a single bacterium
  • no sexual reproduction, they have gene exchange includes swapping plasmids
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8
Q

how much bacterium in a gene?

A

The various genes, about 1200 in a typical bacterium, are arranged along the length of the chromosome, like beads on a string.

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9
Q

Eukaroyte characteristics

A
  • have several orders of magnitude more DNA than prokaryotes
  • usually linear, not circular.
  • every cell has the same DNA, only a fraction of the genes are active, others are permanently “turned off” during development.
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10
Q

What are chromosomes?

A

linear strands of DNA

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11
Q

what are histones?

A

important and very evolutionarily conservative proteins

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12
Q

What are Nucleosomes?

A

Loops of DNA are wrapped around one histone (like thread around a spool), and locked in by a second

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13
Q

What is Mitosis?

A
  • Mitosis, the duplication of the genetic material within a eukaryote cell, is worth mentioning here because of what it IS and what it IS NOT.
  • It IS a duplication of the genetic complement of a eukaryote cell. Since it is usually followed by cell division, it can lead to growth, in a multicellular organism, or asexual reproduction, in a single-celled organism.
  • It IS NOT a means of producing gametes. In sexual organisms, mitosis is peripheral to sexual reproduction, it serves to give rise to cell types which ultimately “kill themselves off” by splitting and splitting again, into four, very different, cells.
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14
Q

Sexual reproduction?

A

-type of reproduction, a sharing of genetic material, to form an individual with equal contributions from two separate parents.

This involves:
The formation of haploid sex cells, called gametes, from a diploid cell, a process called Meiosis.
Syngamy (or, fertilization), a combination of genetic information from two separate cells to form a diploid cell, called a zygote.

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15
Q

Diploidy?

A

state of having two copies of every single gene-like pairs of shoes, pairs of gloves, pairs of stereo speakers.

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16
Q

homozygous?

A

genes, these copies are identical matches

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17
Q

heterozygous?

A

subtle differences between the two copies

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18
Q

Meiosis?

A

process by which a single diploid cell gives rise to four, genetically different, haploid cells.

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19
Q

crossing over (related to meiosis)?

A

Four strands (two homologous chromosomes, composed of two identical strands each) cluster in structures sometimes called tetrads, along a plane in the center of the dividing cell. A process called “crossing over” may occur at this time.

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20
Q

What is the most common meiotic error?

A

nondisjunction, where an entire homologous pair of chromosomes migrates to the pole of a cell, without splitting.

-If this happens to a single pair, it causes either a trisomy, or a monosomy, in the resulting offspring.

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21
Q

what happens during fission?

A

the cell membrane splits into two, one loop of DNA ends up in each new “daughter

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22
Q

what does eukaryote DNA look like?

A

usually linear not circular

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23
Q

Meiosis

A

a single diploid cell with two redundant sets of DNA, and produces four haploid cells, each with a single set of DNA
These four cells all have DIFFERENT sets of alleles, although they have the same genes

24
Q

recombination

A

which is a result of crossing over, new combinations of alleles on chromosomes may arise.

25
Q

assortment

A

By randomly selecting one, or the other, chromosome from a diploid set, to form a haploid set, an enormous number of potential gametes arise.

26
Q

crossing over

A

cytological phenomenon that occurs during the first of the 2 meiotic divisions

27
Q

locus

A

location, place where variation can occur

28
Q

Meiosis does NOT

A

produce new genes or new alleles

29
Q

Meiosis DOES

A

create new combinations of chromosomes, and new combinations of alleles on chromosomes

30
Q

Segregation

A

which a gamete comes to have only one of the two alleles its parent possesses, for every gene. It is random, and it occurs because of the separation of homologous chromosomes during the first meiotic division.

31
Q

Assortment

A

that most eukaryotes possess many pairs of chromosomes, it is segregation at two or many loci simultaneously. Assortment is responsible for the variation in gametes created by the random selection of chromosome from each pair into gametes

32
Q

linkage

A

When genes are on separate chromosomes, it is said that they assort independently. When they are on the same chromosome, they tend to get passed on as a unit, which can only be broken up by recombination

33
Q

Attributes (type of variation)

A

qualitative variables, can be scored, but not fall into a continuum
ex= eye color, political party, blood type, gender

34
Q

Quantitative, or measurable, variables (type of variation)

A

fall along a measurable axis, and can be measured to observe their place relative to others.

35
Q

Discontinuous measurable variables (type of variation)

A

fall into discrete intervals. Examples: shoe size, number of mates, number of arrests for drunk driving

36
Q

Continuous measurable variables (type of variation)

A

do not fall into discrete intervals, they exist along a continuum. Examples: height, weight, age,

37
Q

distribution of value

A

reflects the number of individuals possessing each value for the trait

38
Q

statistical population

A

population has a distribution of values for the variable

39
Q

Types of distributions

A
  • Normal (bell curve)
  • Bimodal (two bell curves)
  • Multimodal (more than two curves)
  • skewed (uneven bell curve)
  • Kurtosis (3 curves, one high, one middle one low)
40
Q

Codominance

A

sometimes called incomplete dominance) is the allelic interaction where, in the heterozygous state, both alleles are expressed (for attributes), or the heterozygote is in between the phenotypes of the homozygous individuals for those alleles (in the case of measurable characters

41
Q

Do all loci have multiple alleles?

A

No, only a small percentage of loci have multiple alleles, 1-5% or less

42
Q

How many Loci are there?

A
  • bacteria -1,200 genes
  • yeast- 5,000
  • Drosophila melanogaster- 10,000
  • Humans- 20,000 protein coding genes
43
Q

Phenotype

A

its observable characteristics.

44
Q

Genotype

A

its genetic composition of alleles.

45
Q

norm of reaction

A

the pattern of phenotypic expression of a particular genotype across different environments.

ex= tall plants grow at low elevation roadsides, and much shorter plants grow in the mountains

46
Q

Gregor Mendel

A

He conducted experiments on the garden pea, Pisum sativum, a species that exhibits variation for several interesting characters: pod color, seed color, flower color, height, etc.. These differ because of alleles at a single locus.

was among the first scientists to think in quantitative, rather than strictly qualitative terms

The resulting offspring (the F2) are 75% purple-flowered and 25% white flowered

47
Q

Inheritance is particulate (mendel)

A

“particles” called genes carry the information that makes parents tend to resemble their offspring.

48
Q

law of segregation (mendel)

A

“particles” segregate, so that individuals with two particles produce gametes with only one particle

49
Q

law of independent assortment (mendel)

A

“particles” for each gene segregate independently of each other

50
Q

true breeding P1

A

the parents always resemble the offspring.

51
Q

F1

A

When they are artificially crossed (garden peas normally self-fertilize),

52
Q

test cross

A

used to determine whether two loci are linked.

53
Q

Drosophila melanogaster linkage example

A

recessive allele for the sepia locus causes flies to have very dark colored eyes. The recessive allele at the ebony locus causes the fly to have very dark body color.
A male from a true breeding line of sepia eyed-ebony bodied flies is crossed to a female from a true breeding line of red eyed, tan-bodied flies (the “wild type”).
The F1 are “Wild Type”
With no linkage, the expected proportion of sepia-eyed, ebony bodied flies is 25%.

54
Q

Homogametic sex

A

sex containing two like sex chromosomes. In most animal species these are females (XX).

55
Q

Heterogametic sex:

A

sex containing two different sex chromosomes In most animal species these are XY male

56
Q

sex linked traits in humans

A

-Hemophilia
-Duchenne’s Muscular Dystrophy
-Red-Green Color Blindness
(recessive exhibiting characteristic pattern of inheritance)
(female can be a heterozygous carrier, but a man can’t)

57
Q

genetically modified organism

A

organism that has undergone human manipulation of its genome via genetic engineering techniques
maize
glo fish

Biology 101 (3 decks)

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