Unit 2 test (Ch. 10-15) Flashcards
(261 cards)
1
Q
What is a gene?
A
It’s a discrete unit of hereditary info
2
Q
what does a gene consist of?
A
consist of a specific nucleotide sequence in DNA
3
Q
What kind of DNA sequences make proteins?
A
Coding DNA sequences
4
Q
What kind of DNA sequences make funbctional RNA molecules?
A
Non-coding DNA sequences
5
Q
What is a genome?
A
Genetic material of organisms/virus, including non-coding DNA sequences
6
Q
True or false?
Genome size corresponds with the number of genes in an organism/virus.
A
False. It does not correlate with the number of genes.
7
Q
approximately how many genes in a genome?
A
21,000
8
Q
What has the lowest coding gene density due to large amount of non-coding dna
A
Mammals
9
Q
what is the structure of DNA in Eukaryotic cells?
A
Form of Chromatin
10
Q
What are DNA molecules bound to in eukaryotic cells?
A
special proteins called Histones
11
Q
when DNA and histones condense… it’s called?
A
chromatin
12
Q
what is an example of a histone?
A
H2A, H2B,H3,H4
13
Q
Why is DNA bound to histones?
A
to condense into chromatin and protect it.
14
Q
what is a nucleosome?
A
DNA wrapped around a histone
15
Q
what are the 2 types of chromatin?
A
Euchromatin and heterochromatin
16
Q
what is euchromatin?
A
loose and found througout the nucleus when cell divides (not easily visible)
17
Q
Genes can be expressed in this form. Which chromatin is it?
A
Euchromatin
18
Q
why can euchromatin allow genes to be expressed?
A
because the genome is active
19
Q
what is heterochromatin?
A
Tightly packed, darkly stained and found close to nuclear membrane.
20
Q
why cant genes be expressed in heterochromatin?
A
because a portion of the genome is inactive so that portion of the genome will not be able to express it’s genes.
21
Q
what loosens the euchromatin?
A
acetyl groups on histones
22
Q
what causes the heterochromatin to condense?
A
Deactylation and presence of methyl groups on cytosine
23
Q
How do histones condense chromatin? (Turn into heterochromatin?)
A
-Since DNA is -ve and histones are +ve
-they attract.
-acetylation removes the =ve charge on histones to loosen
-methylation of cytosine can help recruit proteins to the area that will help condense chromatin
24
Q
what is Epigenetics?
A
the process of activating and deactivating genes through chemical modification
25
what roles does epigenetics involve? (4)
-cell specialization
-oncongentics process (cancer)
-disease
-development
26
what is the central dogma?
It is a theory stating the genetic info flows through DNA molecules to RNA to proteins.
27
What is gene expression?
Process where a gene is turned on in a cell to make RNA and proteins: 2 steps are transcription and translation
28
what does gene expression use and what do the used things do?
uses: mRNA, rRNA, tRNA
do: translates genetic language into protein language
29
what is the minimum number of nucleotides used to generate amino acids diversity?
3 (4^3=64)
30
what is the smallest unit of length that can code for all amino acids?
triplets of nucleotide bases (4^3)
31
what are the genetic instructions for a polypeptide?
DNA is written as a series of non-overlapping, 3 nucleotide words
32
What are the 3 nucleotide words called?
Triplet codes which are codons
33
The anatomy of a gene: what is the form of DNA?
Chromatin
34
The anatomy of a gene: what is a gene specifically?
Stretches of DNA that codes for proteins (coding DNA)
35
The anatomy of a gene: gene expression relies on something important? What is it?
It depends on the Regions of DNA
36
The anatomy of a gene: What is the promoter?
Region where the protein binds to when a gene is going to be expressed
37
What is a gene region that will be transcribed called?
Coding region
38
What does a coding region consist of (2 points)?
-Star point
-Termination sequence
39
At the termination point, how does the transcription stop?
A short codon stops the transcription
40
What does non-coding DNA include?
Sites of genes that make functional RNA or regions of DNA with other functions
41
What type of DNA is a genome composed of?
Non coding DNA but excluding genes that make functional RNA
42
What type of DNA does transcription and translation of a DNA sequence use?
non coding DNA
43
Sites of non coding DNA regions?
Genome, gene expression, centromeres, telomeres
44
What is a telomere and centromere?
Telomere are the ends of a chromosome which eukaryotes have evolved special non coding DNA sequence to protect the genes from being eroded.
The centromere are where the spindle fibres attach to the chromosome during cell division
45
Do telomeres contain genes or genomes?
Neither. Telomeres contain specific DNA sequences and proteins that protect genomes by postponing the erosion of genes located at the ends of the dna molecules
46
What is the telomeres for humans? Where is it found?
Found at the 6th nucleotide sequence: TTAGGG
47
Do telomeres shrink or grow after cell division?
Shrink
48
What catalyses the lengthening of telomerase in stem cells?
Telomerase
49
What does an organism have to do to lead a specific trait by dictating the synthesis of proteins or RNA molecules?
Organism must inherit DNA
50
Where does transcription start in a eukaryotic cell?
The nucleus
51
What is the main purpose of transcription?
To use the genetic info in the form of dna as a template strand to generate a the molecule of rna
52
What are the stages of transcription?
-initiation
-elongation
-termination
53
What happens in initiation of transcription?
-transcription factors inhibit promoters (region to be transcribed) (collection of proteins) mediate binding of RNA polymerase II.
-RNA polymerase then binds to strands and splits the double helix
54
What happens during elongation of transcription?
-RNA polymerase moves down DNA molecule (strand being transcribed) in 3’-5’
-RNA polymerse then moves along the DNA strand, untwists the double helix and exposes the 10-20 nucleotides/time.
55
can there be more than 1 RNA polymerase to transcribe a gene at the same time?
yes, many RNA polymerase can transcribe a gene at the same time.
56
What does the RNA polymerase synthesize?
mRNA transcript
57
By having more than 1 RNA polymerase, what can they make mulitples of?
transcripts
58
How can the RNA polymerase add nucleotides?
Only add nucleotides to the 3' end...(previous nucleotide)
59
what happens during the termination of transcription? What will the RNA polymerase reach?
-Termination sequence
60
what is the termination sequence in transcription?
an area where the transcript (like mRNA) undergoes modifications in the nucleus.
61
how does the transcript leave the nucleus?
through the nuclear pores
62
what happens to the gene expression after the termination of transcription?
gene expression continues with translation
63
what is the main purpose of translation in gene expression?
where the mRNA is read and translated into a string of amino acids, synthesizing proteins
64
what is the mRNA transcript used for in gene expression?
Language of mRNA is used to translate a polypeptide
65
where does translation in gene expression occur? (2)
in the rough ER or the cytosol
66
how many codons are there in translation?
64
67
how many codons are there in an amino acid?
20
68
if the number of codons in translation exceed the number of codons in amino acids, how does gene expression even work?
There are more corresponding codons for amino acids, so they actually have more than 20 and more than 64.
69
Is the genetic code important? If so, why?
The genetic code is redundant because it limits the impact of mutations. There are more than 1 codon for an amino acid meaning there are alot more combinations and diversity among a protein
70
How long is the transcript tRNA?
approx. 80 nucleotides
71
what does tRNA contain? What can this thing that it contains do?
-Anticodon (AAG, AAC, GCA)
It can base pair with the complemenatry codon of mRNA
72
At the other end of the tRNA molecule, there is a...
Binding site for specific amino acid to attach to ribosomes
73
What do the ribosomes do in translation in gene expression?
They synthesize polypeptides
74
How do ribosomes synthesize polypetides?
-they facilitate coupling of tRNA ***anticodons*** with mRNA ***codons*** to grow polypeptide chain
75
What subunits does the ribosome have?
-Large subunit
-small subunit
76
what are the subunits of ribosomes composed of? (2)
proteins and RNA (2/3 of mass)
77
Why do ribosomes take it's shape and function the way it is?
Due to rRNA
78
What is the transcript rRNA?
Catalyst of peptide bond formation, acts as an enzyme
79
Why is the ribosome in 2 subunits, what is the main function of it's shape being like that?
The function of the structure is to bring together the transcript mRNA and tRNA.
80
What does the large subunit of the ribosome contain? (hint: think monkey)
3 tRNA ***Binding sites***
-Aminoacyl tRNA site (A site)
-Peptidyl tRNA site (P site)
-Exit site (E site)
APE!
81
If the RNA transcript is the coding strand, what is the RNA transcript complementary to?
It is complementary to the ***template strand***
82
In transcription, where are the codons found?
Found on mRNA
83
What are the steps of translation?
-Initiation
-Elongation
-Termination
(different from transcription though)
84
What does the ribosome's large subunit have to do with the steps of translation?
Initiation= P-site
Elongation= A-site
E-site,
Cycles until...
Termination
85
what happens at the p-site in initiation of translation? (3)
-small ribosomal subunits bind to mRNA scanning for start codon (AUG) the bind once found
-tRNA binds to mRNA at AUG (start codon) and transports anticodon (UAC, complementary) to start codon
-Large ribosomal subunit then binds with the help of GTP (energy)
86
what happens at the a-site in elongation of translation? (4)
-Anticodon of a-site base pairs with complemntary mRNA codon
-Hydrolysis of GTP increases accuracy & efficiency in step
-Translocation of a-site --> p-site & p-site --> e-site using GTP
-New cycle starts back at a-site
87
What happens at termination of translation?
-Elongation ends @ stop codon arrival (UAA, UAG, UGA)
-Release factor binds to A-site then dissasembles ribosome to stop translation
-Release factor also frees polypeptide
88
what is the release factor in translation?
Appears in termination of translation and it is a protein that binds to a-site, dissasembling the ribosome and freeing the polypetide, stopping translation.
89
After termination, what happens to the polypeptide in translation? (End of translation)
protein folds in cytoplasm or in LUMEN/membrane of the rough ER. The protein either stays in the cell, gets secreted, or gets incorporated into a membrane.
90
What is a mutation?
a change/changes in nucleotide sequence of an organism's DNA or a virus' DNA/RNA
91
what are mutations responsible for?
huge diversity of genes
92
why are mutations responsible for huge diversity of genes?
because mutations are the ultimate source of new genes
93
what are small-scale mutations?
Point mutations
94
what are point mutations?
changes in a single nucleotide pair of a gene
95
what happens if the point mutation occurs in cells that produce gametes?
mutation may be transmitted to offspring
96
what happens if the mutation has an adverse effect on ***phenotype*** of the organism?
Mutant condition may be reffered to as genetic disorder or hereditary disease
97
what happens if point mutation occurs in somatic cells?
It is **Non-consequential **
-It can ***result in dysfunctional cells*** or can be a ***precursor to generation cancerous cells***
98
What are the 5 point mutations?
-Base-pair substitution
-Silent mutation
-Missense mutation
-Nonsense mutation
-Insertion & deletion mutation
99
what is a base-pair substitution mutation?
Replacement of 1 nucleotide & it's partner as well
100
What is a silent mutation?
Base pair substitution had zero effect of coded protein because of the redundancy of genetic code (ATA --> ATA still after we changed the base pair)
101
What is a missense mutation?
Base pair substitution that changes 1 amino acid to another
102
what happens to the protein after undergone a missense mutation?
-May have little effect on protein making it similar to the 1 it replaced.
-New amino acid may be in the same region where the exact sequence of amino acids are NOT essential to function
103
what is an example of a missense mutation?
Sickle-cell anemia
104
what is the evolution of sickle cell anemia?
-New amino acid has a different nucleotide
-sickle cell anemia was in a crucial region for folding and folded wrong, becoming non-functional/impart a new property
*In this case*, the sickle cell anemia's subunit differs from the normal subunit where the oxygen capacity is reduced in sickle cell anemia
105
what is a nonsense mutation?
Base pair substitution that changes amino acid codon --> stop codon
106
what are the consequences of nonsense mutations?
-causes translation to be terminated ***prematurely***
-the new polypeptide is ***shorter***
-most nonsense muations result in non functional proteins
107
What starnd does the base pair change during mutations? DNA template strand, or mRNA?
Template strand, the original.
108
what is an insertion and deletion mutation?
Adds or removes nucleotide pairs ina gene
109
what are the consequences of insertion/deletion mutations?
-they have more disastrous effects on resulting protein
-They cause frameshift mutations if reading frame of genetic message is altered
110
How do insertion mutations happen?
They produce a polypeptide with an ***early stop codon ***by an addition of a base pair
111
How does a deletion mutation happen?
Disrupts the stop codon, producing a much longer polypeptide by the deletionof a base pair.
112
What are mutagens?
Interact with DNA in ways that cause mutations
113
what are physical mutagens?
Include ***ionizing radiation***, like UV light
114
What are nucleotide analogues in chemical mutagens?
A nucleotide analogues are chemicals that are similar to normal nucleotides but*** pair incorrectly during DNA replication***
115
what do chemical mutagens do?
Some interfere with DNA replication by inserting themselves into DNA & distorting the double helix
116
2 types of cell division?
mitosis and meiosis
117
mitosis divides what type of cells?
somatic cells
118
meiosis divides what type of cells?
gemetes or sex cells
119
what does mitosis result in?
identical cells
120
what does meiosis result in?
gametes with 1/2 the number of chromosomes as original cell
121
what are gametes?
sperms and eggs
122
What is the cell cycle?
between the formation of the cell and when it divides to form 2 new daughter cells
123
Cell cycle consist of 3 things...
-Growth of cell following cell division
-copying of genetic info
-distribution of copies to daughter cells
124
Cell cycle is made up of 2 main phases:
-Interphase
-Mitotic phase
125
what takes up 95% of cell cycle (cell's life)?
interphase
126
What does interphase consist of?
-G1
-s
-G2
127
what happens during G1 of interphase?
Period of active growth, regulatory proteins synthesized
128
what happens during S phase of interphase?
Prep for cell to make replication of it's DNA
An exact copy of each chromosome is produced
129
What happens in G2 phase of interphase?
2nd growth phase where*** cell increases in size*** slightly, ***duplicate centrosomes*** in prep for mitotic phase
130
What is a parental duplex in s-phase of interphase?
Parent DNA strands that separate & serve as templates for synthesis of daughter strands
131
what is the DNA polymerase in interphase?
An enzyme responsible for making new 'daughter strands' of DNA
132
Is DNA replication semiconservative? If so, why?
yes, because after replication, each new DNA molecule will consist of 1 parental duplex and 1 new synthesized daughter strand.
133
what are sister chromatids?
copied chromosomes containing the same genetic material and attached at the centromere
134
What form is the DNA when cells AREN'T dividing?
Chromatin; long, unpackaged fibers
135
When cells prepare to divide, what form is the DNA?
Chromatin is Condensed into chromosomes
136
How many ***pairs*** of chromosomes do humans have?
23
137
How many chromosomes from a mother?
23
138
how many chromosomes from a father?
23
139
how many chromosomes does a human have?
46 (23 pairs)
140
How many pairs of autosomes does a human have?
22 pairs
141
how many pairs/pair of sex chromosome(s) does a human have?
1 pair
142
what are homologous chromosomes?
a maternal and paternal pair of chromosomes that are not identical but similar because of their alleles.
143
why are homologous chromosomes similar?
because they share the same genes but may have different versions of these genes called alleles. This is what causes distinguishable differences
144
if there are 22 pairs of autosomes, how many pairs of homologous chromosomes?
22 pairs
145
What is the ploidy number?
number of complete sets of chromosomes in a cell
146
Cells with 1 complete set of chromosomes are?
ploidy number is haploid (n) which are gametes
147
cells with 2 complete sets of chromosomes are?
ploidy number is diploid
(2n) which are somatic cells
148
What are the phases of mitosis? (5)
-Prophase
-Prometaphase
-metaphase
-anaphase
-telophase & cytokinesis
149
What goes on in prophase? (3)
| Mitosis
-Chromatin condenses into chromosomes
-Duplicated centrosomes move around nucleus
-Microtubule fibers extend between centrosomes forming mitotic spindle
150
What goes on in prometaphase? (3)
| mitosis
-Nuclear envelope breaks down
-Centrosomes at opposite poles on cell
-some microtubules attach to chromosome at the centromere via the kinetochore
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What goes on in metaphase? (2)
| mitosis
-Chromosomes line up at the metaphase plate
-Kinetochores attached to microtubules on each end of the cell
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what goes on in anaphase? (4)
| mitosis
-Centromeres break forcing sister chromatids to separate
-Chromosomes pulled to opposite ends of the cell
-Cell elongates
-each pole of cell has complete set oif chromosomes
153
what goes on in telophase and cytokinesis? (8)
| mitosis
Telophase: (4)
-1 copy of each chromosome is at opposite ends of the cell
-chromosome starts to loosen and become less coiled
-spindle fibers disapear
-nuclear envelope reforms
Cytokinesis: (4)
-Cleavage furror forms
-Pinching inward of cytoplasm
-Daughter cells contain identical DNA and volume of cytoplasm
-Cell then goes to G1 for another round of cell cycle or G0
154
what organelle do plants not contain. Does this have an effect on it's mitotic phase?
No centrioles but still has spindle fibers so it doesn't effect it.
155
What can't the plant cells do in cell division?
They cannot pinch like animal cells in cytokinesis
156
How are plant cells separated in mitosis?
The cell plate because they cannot pinch
157
do all cells divide?
No.
158
do cells that shouldn't divide, divide anyway?
yes, some can which cause trouble
159
when should a cell divide? Give an example.
at the right time, like during an injury
Just enough cells must be produced for optimal function
160
does cell division happen in specific locations?
yes, only properly placed cells will divide
161
when we say only properly placed cells will divide, what do we mean by that?
a detached cell that wanders into new tissue won't divide and establish itself in this new location
162
What cells does cell division occur in? For controlled cell cycle?
healthy cells, abnormal cells should NOT undergo cell division
163
What controls cell division? what are these 3 things called?
regulatory mechanisms:
-Receptors
-Anchoring proteins
-Regulatory proteins
164
how does a receptor control the cell cycle?
Monitors surface molecules on neighbor cells which monitor cell density in tissues
165
what is density dependent inhibition of growth?
this is just a scary way of saying the receptors monitor when cell gaps need to be filled. Like say some cells are scraped away, the receptors are going to ensure that gap is filled so that the cell can go through the cell cycle
166
how do anchoring proteins control the cell division?
They ***hold*** cells in place within their tissues and prevent cells from establishing themselves in other tissues if disloged
167
how do regulatory proteins control cell division?
They check on cellular function and DNA during cell cycle. Basically checks on them during cell checkpoints; G1, S, G2.
This protein is basically a guide for cell cycle checkpoints and makes the cell check itself at specific times to asses if its ok.
168
Regulatory proteins: what is the most important checkpoint and why?
G1, because it checks for DNA damage. Cell either recieves a go ahead to go to s-phase or go to G0 if DNA is shit
169
Regulatory protein: G2 checkpoint assesments? (2)
-any DNA damage?
-has all DNA been replicated?
170
Regulatory protein: m checkpoint assesments? (2)
-are all chromosomes properly alligned?
-Are kinetochores attached to spindle fibre?
171
what is the most important regulatory protein?
p53, transcription factor
172
what does p53, transcription factor classify as?
A tumor supressor protein (i.e make cancer less severe, survivable)
173
what is a cool thing that the p53, transcription factor do?
it can pause the cell cycle and initiate DNA repair
174
can p53 always save the DNA?
No, if it can't it induces cell to death or apoptosis
175
what is apoptosis?
cell suicide, programable death
176
what happens if damaged cells continue to divide?
they could impact the overall function of it's tissue, spreading whatever mutation that cell has developped, like cancer
177
what is cancer?
uncontrolled and unregulated cell growth which can occur in all tissues of the body
178
what is the cause of cancer?
changes/damages in DNA of a cell--> makes the cell ignore regulatory mechanisms
179
what causes DNA damage?
DNA mutations
180
what are the causes of DNA mutations in the cell cycle?
-chemical causes like tobacco smoke
-physical causes like ionizing radiation
-infectious causes like bacterial, fungal and viral infections
181
why are the DNA mutations such a viscious cycle?
because as. amutated cell divides, the cell just quires more and more mutations because the DNA never gets repaired
182
what is a benign tumour?
unusual cell growth in a tissue that is not cancerous or invasive
183
do benign tumour's invade other tissues?
no
184
What is metastasis?
when cells multiply and invade other tissues causing tissues damage
185
what is the consequence of metastasis?
malignant tumours
186
what is angiogenesis?
when tumours induce the growth of blood vessels to feed themselves
187
what is true cancer?
interuption of tissue function leading to organ failure and death
188
what is the difference between asexual and sexual reproduction?
-asexual= offspring is identical to parent cells
-sexual= offspring is NOT identical to parents
189
which has more genetic variation, asexual or sexual reproduction?
sexual reproduction (meiosis) because they have the production of gametes
190
How many chromosomes do somatic cells have?
46 chomosomes
191
how many chromosomes do gametes have?
23 chromosomes
192
what is a female and male gamete?
sperm and egg
193
what is meiosis?
progenitor cells that produce gametes and undergo cell division but the sexual reproductive way.
194
what does meiosis produce?
cells that have 1/2 the # of chromosomes found in the orginal cell and are gentically different from parent cells
195
why does meiosis produce 1/2 the # of chromosomes?
because if it was diploid sperm(2(23)) fertilized diploid egg(2(23)), --> zygote would have 92 (2(46)) chromosomes. Number of chromosomes in each zygote with double each time
196
what is the reason for homologous chromosomes?
meisosis
197
what is a homologous chromosome?
1 maternal pair of chromosomes and 1 paternal pair of chromosomes which are NOT identical but very similar because they have the same genes but different versions of these genes called alleles
198
Are gametes diploid?
no they are haploid (n)
-sperm=n
-egg=n
199
if the gametes are haploid, then the zygote is haploid right?
no the zygote is diploid
200
what does it mean when a cell is diploid?
it means; say there is a cell with 2 types of chromosomes; pink and blue, by it being diploid, there are 2 pink chromosomes and 2 blue chromosomes.
if it were haploid, there would only be 1 pink chromosome and 1 blue chromosome
201
what are autosomes?
not sex chromosomes
202
how many autosomes in a human?
22 pairs of chromosomes which is 44 chromosomes out of 46 which are not sex chromosomes
203
how is meiosis genetically diverse? what process does it go through for it to have such diversity?
Meiosis 1 and meiosis 2
204
what does Meiosis start with?
Interphase: G1, S, G2
205
after interphase in meiosis, what happens?
cell goes through prophase 1, METAPHASE 1,...
206
what does meiosis skip that mitosis doesn't?
prometaphase
207
by the end of meiosis 1, how many cells are there?
2 cells containing the homologous chromosomes
208
are sister chromatids and homologous chromosomes the same?
no, the sister chromatids are identical and used in mitosis
homologous chromosomes are genetically different and used in meiosis
209
after meiosis 1, the 2 cells...
undergo meiosis 2 where they produce 4 haploid cells
210
During interphase, cell undergoes s-phase, so before meiosis 1 starts, what happens to the individual chromosomes?
they are replicated into sister chromatids making the cell diploid
211
During prophase 1, what happens?
-chromatin condenses into chromosomes
-nuclear envelope breaks down
-centrosomes migrate to opp ends of cell connecting their spindle fibres
-homologous chromosomes form a tetrad and exchange genetic segments at the chiasma (synapsis)
212
what does the synapsis allow?
cross-over of non sister chromatids
213
what does crossing over lead to?
recombinant chromatids
214
what are recombinant chromatids?
they are the non sister chromatids that exchange genetic variation at the chiasma when synapsis happens
215
what happens at metaphase 1?
spindles move the tetrads and line them up along the midline by the microtubules attached to the centromere via the kinetochore
216
in metaphase 1, how do the homologous pairs of chromosomes (recombinant twin pairs) line up?
the tetrad orients randomly
217
what happens in anaphase 1?
the microtubules pull the recombinant chromatids to opposite ends of the cell, separating the homologous chromosomes, now the cell will consequently have 46 chromatids
218
what happens during telophase 1 and cytokinesis
-nuclear envelope reforms
-clevage furrow forms and sister chromatids remain together
-daughter cells of meiosis 1 are now haploid because of the crossing over
219
after meiosis 2, what happens to the daughter cells?
daughter cells are now 4 haploid cells with their own genetic variation
220
what is gametogenesis?
spermatogenesis and oogenesis
221
Gametogenesis is a mix of...
mitosis and meiosis
222
how does gametogenesis work?
germinal epithelium undergoes mitosis
-the resulting identical cell undergoes meiosis forming 4 haploid cells
223
In asexual reproduction, how do the cells rely on generating diversity?
through mutations of the genes only
224
in sexual reproduction, how does the cell rely on generating diversity?
through the crossing over and the random alignmnet of tetrads along the midline
225
what are alleles?
mutations of genes that have created different versions of these genes
226
what is independent assortment?
when the homologous chromosome pairs orient randomly at the metaphase 1 of meiosis. the possible number of combinations is 2^n so for humans it is 2^23 which is over 8.4 million possible combinations
227
Why does random fertilization contribute to genetic diversity?
because any sperm can fuse woth any ovum
228
what does the evolutionary significance have to do with genetic variation?
natural selection results in the accumulation of genetic variations favored by the environment
229
what does non coding DNA include?
sequences that form our telomeres, centromeres, rRNA and tRNA
230
what do genes include?
sequences of DNA found on chromosomes that codes for proteins
231
what is a gene locus?
each gene that exists on a specific chromosome at a specific location on that chromosome
232
Do humans share the same genes?
yes, but we all have different versions of these genes which is what makes us different from eachother called alleles
233
what do diploid organisms contain in context of chromosomes?
2 copies of each chromosome
234
where do diploid organisms recieve there chromosomes from?
chromosome 1 comes from the mom
chromosome 2 comes from the dad
235
what are pairs of chromosomes in a cell reffered to as?
homologous chromosomes
236
do homologous chromosomes contain the same genes?
yes but they may have different versions of these genes called alleles
237
what is an example of a gene?
eye color
238
what is an example of the alleles of a gene? (Say the gene is eye color what are the alleles?)
there is an allele coding for brown eyes and an allele coding for blue eyes
239
what if a person had a homologous chromosome, where 1 of the chromosomes in that pair had an allele for blue eyes and another chromosome for brown eyes? How can we tell if they will have blue or brown eyes?
1 of the alleles would be dominant over the other
240
what does heterozygous mean?
It means they have more than one allele: Bb, Aa, Tt
241
what does homozygous mean?
It means they have the same allele: BB, bb, AA, aa
242
What is models of inheritance?
It deals with the transmission of traits from one generation to the next.
243
what are traits encoded by?
Traits are encoded by genes
244
why do traits vary in inheritance?
because the genes that encode it have different versions of themselves called alleles
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What hypothesis did they form before Gregor proved there were alleles?
Blended inheritance; like paint mixing
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why is blended inheritance inacurate
because some traits would skip generations
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what did mendel examine for his discovery?
pea plants which could be ***observable*** and ***existed in 2 traits.***
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what did Mendel begin breeding with which was very lucky for him?
***true breeding*** individuals (flowers)
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What was Mendel's big discovery in his experiment? (what did he cross and what happened?)
He crossed a true breeding purple flower with a true breeding white flower and had an outcome of all purple flowers.
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what did Mendel call his true breeding purple flower and true breeding white flower cross?
P-cross (parent generation)
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what did Mendel call his result of the p-cross?
F1 generation is the result of all purple flowers
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Can a gene exist in more than 1 form?
yes
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How are alleles transmitted from the p-cross to the F1 generation?
Through the law of segregation
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what is the law of segregation in inheritance models?
-describes how alleles are pieces of DNA that occur on chromosomes.
-These chromosomes are then replicated and undergo meiosis to form gametes with 1 of each chromosome and consequently 1 allele of each gene
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What does a human zygote have?
1 pair of homologous chromosomes for each 22 autosomes and 2 sex chromosomes
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in females, what are there sex chromosomes called?
homologous chromosomes because they have XX
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do males have homologous sex chromosomes?
no they have XY
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What is a genotype?
combination of alleles in a particular individual
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what is a phenotype?
Physical manifestation of an individual's genotype. (i.e: Pp, pp, it depends on the alleles and which are dominant or not)
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What is true breeding?
it involves 2 different homzygous alleles crossed
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What is the point of punnet squares?
probabilities that offspring born of a cross will present with a specific genotype or phenotype
