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Chapter 4 Flashcards

1
Q

What is DNA’s structure?

A

Long, thread-like molecule w/ uniform diameter and varied length

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2
Q

How many DNA molecules in the nucleus of human cells?

A

46 individual, or 23 pairs

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3
Q

What type of molecule is DNA?

A

A polymer of nucleotides

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4
Q

What are nucleotides made up of?

A

A sugar, phosphate group, and nitrogenous base

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5
Q

What are purines?

A

Double-ring nitrogenous bases. Adenine and guanine

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6
Q

What are pyrimidines?

A

Single-ring nitrogenous bases. Cytosine, thymine, uracil

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7
Q

What are the DNA bases?

A

A, T, C, G

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8
Q

How is DNA shaped?

A

Double helix

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9
Q

Function of DNA?

A

It codes for the synthesis of RNA and a specific protein

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10
Q

What are the DNA base pairs?

A

A-T and C-G

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11
Q

What is a chromatin?

A

A fine, filamentous DNA material complexed w/ proteins, located in the cell nucleus

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12
Q

What is a histone?

A

Protein core

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13
Q

What are nucleosomes?

A

Histones linked together. Chromatin is made of thousands of repeating nucleosomes

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14
Q

What is done before cell division?

A

The cell makes a copy of all nuclear DNA. The copies are called sister chromatids

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15
Q

Where are chromatids joined at?

A

The centromere

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16
Q

Where are kinetochores?

A

The side of each centromere of a chromosome

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17
Q

What does RNA do?

A

Carries out the instructions in DNA and assembles proteins

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18
Q

How does RNA look?

A

One nucleotide chain (not a double helix)

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19
Q

How is RNA structurally different from DNA?

A

It uses ribose instead of deoxyribose as the sugar, and uracil replaces thymine as a nitrogenous base

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20
Q

3 types of RNA?

A

Messenger RNA, ribosomal RNA, and transfer RNA

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21
Q

What is a gene?

A

An information-containing segment of DNA that codes for the production of a molecule of RNA that plays a role in synthesizing proteins

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22
Q

What is a genome?

A

All of the genes of one person

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23
Q

What percentage of genes code for DNA?

A

2%, other 98% is noncoding

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24
Q

What is genomics?

A

The study of the whole genome and its genes and noncoding DNA interact to affect structure and function of whole organism

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25
Q

What is genetic code?

A

A system that enables four nucleotides to code for amino acid sequences of all proteins. The link between mRNA codons and the 20 amino acids

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26
Q

What is a codon?

A

A 3-base sequence in mRNA

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27
Q

What are the stop codons?

A

UAG, UGA, and UAA

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28
Q

What is the start codon?

A

AUG

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29
Q

True or false: any given cell uses 1/3-2/3 of its genes

A

True

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30
Q

What is transcription?

A

DNA codes for mRNA in nucleus

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31
Q

What is translation?

A

mRNA codes for protein in cytoplasm

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32
Q

During transcription, how are base pairs made?

A

C = G
T -> A
A -> U

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33
Q

What is a terminator?

A

Stop codon, a base sequence at the end of a gene signaling stop

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34
Q

What are exons?

A

Segments of pre-mRNA that will be translated into protein

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35
Q

What are introns?

A

Segments of pre-mRNA that must be removed before translation

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36
Q

What are ribosomes?

A

Organelles that read the tRNA message

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37
Q

3 steps of translation?

A

Initiation, elongation, termination

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38
Q

What is initiation?

A

Small ribosomal unit binds to mRNA in cytosol, tRNA attaches at start codon, then ribosomal unit joins complex

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39
Q

h

A

h

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40
Q

What is termination?

A

When a ribosome reaches a stop codon, a release factor binds to it and the finished protein breaks away from the ribosome.

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41
Q

Steps of peptide formation?

A

1) DNA double helix
2) 7 base triplets on the template strand of DNA
3) Corresponding codons of mRNA transcribed from DNA triplets
4) Anticodons of tRNA that bind to mRNA
5) Amino acids carried by those 6 tRNA molecules
6) Amino acids linked into a peptide chain

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42
Q

4 steps of DNA replication?

A

Unwinding, unzipping, building new DNA strands, repackaging

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43
Q

What is the replication fork?

A

The point of DNA opening

44
Q

What happens during the DNA building new strands?

A

The polymerase reads exposed bases and matches their pairs, they work on each strand in opposite directions and make a new continuous strand of DNA. 2 molecules are made from 1

45
Q

What is semiconservative replication?

A

Each daughter DNA consists of one old and one new helix

46
Q

What is a mutation?

A

Changes in DNA structure due to replication errors or environmental factors (radiation, viruses, chemicals)

47
Q

What can mutations do?

A

Some have no effect, some kill cells or turn them cancerous, some cause genetic defects in future generations

48
Q

What is the cell cycle?

A

Cell’s life from one division to the next. Interphase and mitotic phase

49
Q

Subphases of interphase?

A

G1, S, G2

50
Q

Subphases of mitotic phase?

A

Prophase, metaphase, anaphase, telophase

51
Q

What is G1 phase?

A

Interval between cell birth and DNA replication. Cell carries out normal tasks and accumulates materials for next phase

52
Q

What is S phase?

A

Cell replicates all nuclear DNA and duplicates centrioles

53
Q

What is G2 phase?

A

Interval between DNA replication and cell division. Cell repairs replication errors, grows, synthesizes enzymes that control cell division

54
Q

What is M/mitotic phase?

A

Cell replicates its nucleus. Pinches in 2 to form new daughter cells

55
Q

What is G0 phase?

A

Cells that have left the cycle and cease dividing for a while or permanently

56
Q

What is mitosis?

A

Cell division resulting in 2 genetically identical daughter cells

57
Q

Functions of mitosis?

A

Develops a person from a fertilized egg. Growth of all tissues and organs after birth. Replace dead cells and repair damaged tissues

58
Q

What happens during prophase?

A

Genetic material condenses into compact chromosomes. 46 chromosomes total. 2 chromatids per chromosome. Nuclear envelope disintegrates. Centrioles sprout spindle fibers. Some attack to kinetochores of centromeres of chromosomes

59
Q

What happens during metaphase?

A

Chromosomes align on cell equator. Spindle fibers complete lemon-shaped mitotic spindle. Shorter microtubules from centrioles complete an aster which anchors itself to inside of cell membrane

60
Q

What happens during anaphase?

A

Enzyme cleaves 2 sister chromatids apart at the centromere. Single-stranded daughter chromosomes migrate to each pole of the cell as motor proteins in kinetochores crawl along spindle fibers

61
Q

What happens during telophase?

A

Chromosomes cluster on each side of the cell. Rough ER makes new nuclear envelope around each cluster. Chromosomes uncoil to chromatin. Mitotic spindle disintegrates. Each nucleus forms nucleoli.

62
Q

What happens during cytokinesis?

A

Division of cytoplasm into 2 cells. Telophase overlaps into this. Works bc myosin protein pulls on actin in the cytoskeleton terminal web. Creates cleavage furrow

63
Q

When do cells divide?

A
  • Have enough cytoplasm for 2 daughters
  • DNA is replicated
  • Enough nutrients
  • Stimulated by growth factors (chemicals)
  • Neighboring cells die, opening up space
64
Q

When do cells stop dividing?

A
  • Nutrients or growth factors are withdrawn
  • Contact inhibition (not enough space)
65
Q

What is heredity?

A

Transmission of genetic characteristics from parent to offspring

66
Q

How do you inherit chromosomes?

A

You get 1 chromosome from each parent, for each pair of 23 (so 23 pairs, half mom half dad, 46 chromosomes total)

67
Q

How many autosomes?

A

22 pairs

68
Q

How many pairs of sex chromosomes?

A

1

69
Q

What sex is XX chromosomes?

A

Female

70
Q

What sex is XY chromosomes?

A

Male

71
Q

What does diploid (2n) mean?

A

Any cell with 23 pairs of chromosomes (somatic cells)

72
Q

What does haploid (n) mean?

A

Cells containing 23 unpaired chromosomes. Sperm and egg (germ) cells

73
Q

What does locus mean?

A

The location of a particular gene on a chromosome

74
Q

What are alleles?

A

Different forms of a gene at the same locus on 2 homologous chromosomes

75
Q

What are dominant alleles?

A

Capital letter, makes trait appear, masks recessive allele’s effect

76
Q

What are recessive alleles?

A

Lowercase letter, only seen when both homologous chromosomes are recessive

77
Q

What is a genotype?

A

Alleles an individual possesses for a particular trait

78
Q

What does homozygous mean?

A

2 identical alleles for a trait

79
Q

What does heterozygous mean?

A

2 different alleles for a trait

80
Q

What is a phenotype?

A

An observable trait

81
Q

What is a gene pool?

A

Genetic makeup of whole population

82
Q

What is codominance?

A

Both alleles are equally dominant. Phenotypically expressed

83
Q

What is incomplete dominance?

A

Heterozygous person shows phenotype intermediate between traits each allele would’ve produced alone

84
Q

What is polygenic inheritance?

A

Genes at 2 or more loci contribute to a single phenotypic trait

85
Q

What is pleiotropy?

A

One gene produces multiple phenotypic effects

86
Q

How do sex-linked traits work?

A

Carried on X or Y chromosome, and therefore are inherited by one sex more than the other

87
Q

How does colorblindness work?

A

It’s recessive and carried on the X, so it’s more common in men

88
Q

What is epigenetics?

A

A field examining nongenetic changes that alter gene expression and can be passed to offspring

89
Q

What does DNA methylation mean?

A

It’s a mechanism of epigenetic change in which methyl groups are added to DNA, often silencing the gene

90
Q

What does metastasizing mean?

A

Giving off cells that spread and seed the growth of tumors elsewhere

91
Q

What is oncology?

A

Medical specialty dealing with tumors

92
Q

What is tumor angiogenesis?

A

Growth of blood vessels by energy-hungry tumors

93
Q

What are carcinomas?

A

Cancers of epithelial tissue

94
Q

What are lymphomas?

A

Cancers of lymph nodes

95
Q

What are melanomas?

A

Cancer in pigment cells of epidermis (melanocytes)

96
Q

What are leukemias?

A

Cancer in blood-forming tissues

97
Q

What are sarcomas?

A

Cancer in bone, other connective tissue, or muscle

98
Q

What are carcinogens?

A

Environmental cancer-causing agents

99
Q

What is radiation (as a carcinogen)?

A

Ultraviolet rays, X-rays

100
Q

What are chemicals (as a carcinogen)?

A

Cigarette tar, food preservatives, industrial chemicals

101
Q

What are viruses (as a carcinogen)?

A

Human papillomavirus, hepatitis C, and type 2 herpes simplex

102
Q

What do carcinogens do?

A

Trigger gene mutations

103
Q

How many cancers are hereditary?

A

5-10%

104
Q

What are oncogenes?

A

Cause cell division to accelerate out of control. For cancer

105
Q

What are tumor-suppressor (TS) genes?

A

Healthy tumor suppressor genes inhibit development of cancer, mutated or silenced ones leave oncogene action unopposed

106
Q

Why is cancer lethal?

A

Replaces functional tissue in vital organs, steals nutrients from rest of body, weakens one’s immunity, opens door for opportunistic infections

107
Q

What is cachexia?

A

Severe wasting away of depleted tissues

‱ (40 decks)

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