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Biology Lecture Exam 1 > Biology exam #4 > Flashcards

Biology exam #4 Flashcards

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1
Q

Chromosome

A

a structure found inside the nucleus of a cell, composed of DNA tightly coiled around proteins, which carries the genetic information of an organism

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2
Q

Chromatin

A

A condensed structure made up of DNA, RNA, and proteins that forms the chromosomes in the nucleus of a cell

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3
Q

Histone

A

Small, basic positively charged proteins in the cell nucleus that bind to the negatively charged DNA

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4
Q

Nucleosome

A

The basic repeating unit of chromatin, consisting of a section of DNA wrapped around a core of eight histone proteins

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5
Q

Heterochromatin

A

Highly coiled and compacted chromatin in an inactive state

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6
Q

Euchromatin

A

A loosely coiled chromatin that is generally capable of transcription
Active

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7
Q

Histone acetylation

A

The action a reversible process that adds acetyl groups to nucleosomes and looses the structure of the chromatin and when it’s reverse the chromatin tightens

Alters chromatin structure.

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8
Q

Histone acetyltransferases (HATs)

A

The protein that preforms the action
an enzyme that actively adds acetyl groups to histone proteins
It allows DNA to uncoil for transcription

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9
Q

Histone Deacetylase (HDAC)

A

enzymes that remove acetyl groups from proteins, which regulates gene expression and chromatin structure
Alllows the DNA to recoil

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10
Q

What is the composition of chromatin, the material of chromosomes?

A

DNA tightly wrapped around histones

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11
Q

Phenotype

A

The physical appearance of an organism, what creates the characters of the organism

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12
Q

Genotype

A

the genetic makeup for that organism
Refers to Exact pairing of the alleles

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13
Q

Gene

A

The basic unit of heredity passed from parent to child

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14
Q

homologous chromosomes

A

pair of chromosomes in a cell that are similar in size, shape, and gene content

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15
Q

Allele

A

Alternative form of a gene

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16
Q

locus/loci

A

a specific location on a chromosome where a gene or genetic marker is found

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17
Q

Recessive

A

a trait that is only expressed when an individual has two copies of the same recessive allele

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18
Q

Dominant

A

a trait or allele of a gene that is expressed even when only one copy is present

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19
Q

Incomplete dominance

A

When a dominant allele is NOT COMPLETELY expressed when the resssive allele is around
Ex. A RR (red flower) & rr (white flower) make Rr (pink flower)

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20
Q

Codominance

A

Both alleles are expressed, so they are both dominant
Ex. BB (black chicken) and WW (white chicken) make BW (black/white chicken)

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21
Q

Homozygous

A

having two identical versions of a gene, one inherited from each biological parent.

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22
Q

Heterozygous

A

A term that describes having two different versions of the same gene

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23
Q

Hemizygous

A

only one copy of a gene rather than the usual two copies

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24
Q

Principle of Segregation

A

Mendel’s Law
gene alleles, separate into reproductive cells during meiosis

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25
Punnett SquAre
diagram that predicts the probability of an offspring's genotype and phenotype from a cross between two parents
26
Test cross
an individual of unknown genotype is crossed with a recessive individual
27
P generation
the original pair of parents at the start of a genetic cross experiment
28
F1 generation
the first generation of offspring produced by crossing two different parents Offspring of then P generation
29
F2 generation
the result of a cross between two F1 individuals Offspring of then F1 generation
30
Law of Independent Assortment
when reproductive cells develop, different genes separate independently from one another
31
how is sex determined in mammals?
by the presence of sex chromosomes
32
when reproductive cells develop, different genes separate independently from one another (G zero) stage?
Becomes daughter cells
33
What is the goal of mitosis/cytokinesis?
to produce two identical daughter cells
34
unduplicated chromosome
a single, individual chromosome that has not yet undergone DNA replication
35
duplicated chromosome
a chromosome that has an extra copy of a DNA segment
36
sister chromatid
identical copies of a chromosome that are joined together by a centromere
37
Gametes
a reproductive cell of an animal or plant
38
haploid
having a single set of unpaired chromosomes.
39
Diploda
two complete sets of chromosomes, one from each parent.
40
polyploid
a condition where an organism or cell has more than two sets of chromosomes
41
Synapsis
the fusion of chromosome pairs at the start of meiosis.
42
tetrad
A four-part structure that forms during prophase I of meiosis and consists of two homologous chromosomes, each composed of two identical chromatids.
43
Crossing over
is a cellular process that occurs during meiosis when homologous chromosomes exchange genetic material
44
genetic recombination
the process by which DNA sequences are rearranged, resulting in new combinations of alleles in offspring
45
What happens if chromatids do not separate during meiosis?
a phenomenon called "nondisjunction" occurs, resulting in gametes with an abnormal number of chromosomes, which can lead to genetic disorders in the offspring if such a gamete is fertilized
46
Erwin Chargaff founded
the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal
47
Linus Pauling Founded
discovered the spiral protein structure alfa helix
48
Rosalind Franklin founded
Investigated molecules using x ray diffraction
49
James Watson & Francis Crick Founded
Nobel prize for structure of DNA
50
what does the 5' and 3' designations refer to in the DNA structure?
the carbon number on the deoxyribose sugar molecule that is attached to the phosphate group at the end of a DNA strand
51
describe the structural components of the DNA molecuLe
two long strands of nucleotides, each consisting of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base
52
compare/contrast the purine bases (A, G) with the pyrimidine bases (C, T) with regards to shape and size
Purine bases (Adenine, Guanine) are larger and have a double-ring structure, while pyrimidine bases (Cytosine, Thymine) are smaller and have a single-ring structure
53
what are the rules of base pairing
A — T C — G
54
why are GC basepairs stronger?
3 hydrogen bonds instead of 2
55
what provides energy for deoxynucleotides to join to the 3' end of a growing DNA strand?
The high energy phosphate groups
56
how do new DNA strands form in opposite directions?
the enzyme responsible for building new DNA, DNA polymerase, can only add nucleotides in the 5' to 3' direction, forcing the new strands to be synthesized in opposite directions at the replication fork
57
DNA Helicase
an enzyme that separates/ unwind double-stranded DNA into single strands
58
Single-Strand Binding Protein
a protein that binds to single-stranded DNA (ssDNA) and plays a vital role in DNA metabolism
59
Primase
an enzyme that synthesizes RNA primers
60
DNA Polymerase
an enzyme that copies DNA molecules, ensuring the accurate replication of genetic information during cell division
61
why must Primase produce an RNA primer BEFORE DNA Polymerase can build a new DNA strand
DNA polymerase can only add nucleotides to an existing 3'-hydroxyl group on a pre-existing strand, meaning it cannot initiate DNA synthesis on its own
62
what is the role of DNA Polymerase 1 and DNA Ligase in completing lagging strand synthesis?
DNA Polymerase 1 is responsible for removing RNA primers and replacing them with DNA nucleotides, while DNA Ligase joins the newly formed DNA fragments (Okazaki fragments) together, effectively sealing the gaps in the sugar-phosphate backbone to create a continuous strand
63
how is the DNA synthesis machinery involved in DNA repair?
utilizing its ability to synthesize new DNA strands to replace damaged sections of DNA
64
mismatch repair
biological process that corrects errors in DNA replication, such as base-pair mismatches, insertions, and deletions
65
nucleotide excision repair
DNA repair mechanism that removes damage from DNA strands caused by radiation, chemicals, and other mutagens
66
why do linear DNA molecules get shorter with each cycle of DNA replication?
because of the "end replication problem
67
what is the consequence of chromosome shortening? How do cells get around this?
cells eventually reach a point where they can no longer divide, leading to cellular senescence (aging) and ultimately cell death; cells can partially get around this by utilizing an enzyme called telomerase to rebuild telomeres
68
Geneome
DNA of a cell
69
G1 phase
Cell enlargement 1st gap stage
70
S
DNA replication Synthesis stage
71
G2
Preparation for mitosis
72
M
Mitosis
73
G0
Mature cells Quiescent
74
what is the role of Telomerase enzyme?
maintaining the length of telomeres, by adding repetitive DNA sequences to them
75
Telomeres
the protective caps at the ends of chromosomes
76
RNA Primers
short RNA sequences that initiate DNA replication

Biology Lecture Exam 1 (9 decks)

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