Unit 4 Genetics Integrated Science 2

Mammal cells spend 20 hours in ______________ - 90% of the time in the cell cycle(most time spent).

interphase

Occuring ONLY in reproductive cells, _________ is 2 step cell division that produces gametes, or sex cells. This produces 4 daughter cells containing half as many chromosomes as the parent cell and is IMPORTANT for sexual reproduction as it results in gametes(sperm & eggs)

meiosis

In the interphase, _____________ is visible which is meant to package the long strands of DNA into more compact structures

chromatin

In ________, the cell's cytoplasm divides to form two daughter cells and seperate

cytokinesis

In the  ___ phase of interphase, cells get normal cell functions, grows, goes through protein synthesis, makes new organelles, its cytoplasm increases, and doubles in size. This takes from 8-12 hours or a few months

G1

In the ___ phase, otherwise known as the Synthesis phase in the Interphase, the cell synthesizes a complete copy of DNA in its nucleus and duplicates a microtubule-organizing structure called the centrosome(helps separate DNA in M phase)

S

In _________, the cell's nucleus divide along with its DNA. It has 4 stages, prophase, metaphase, anaphase, and telophase before cytokinesis occurs

mitosis

In the ____ phase, the cell resumes to grow through protein synthesis and duplicates organelles in preparation for division(mitosis). This also checks if the DNA is accurately replicated before it enters mitosis

G2

The three phases of Interphase are ___, ___, and ___.

G1, S, G2

______________ bonds allow easy access to the sequences of bases during the DNA replication process

Hydrogen bonds

_________ is the first enzyme to load on at the origin of replication, moving the replication fork forward by unwinding the DNA and breaking the hydrogen bonds between nitrogenous bases

Helicase

DNA polymerase can only make DNA in the 5' to 3' direction, or the _________ _________, which is continuous because DNA polymerase is moving in the same direction as the replication fork(If your adding from 3', then your going from 5' to 3')

leading strand

What are the 4 key features of DNA polymerase

• They need a template
• They can only add nucleotides to the 3' end of a DNA strand
• They cannot start making DNA chain without a primer
• They proofread the DNA chain for wrong nucleotides

______________ bonds help maintain the sugar-phosphate backbone of DNA strand and protect the genetic code inside

Covalent

Cytosine & Guanine pair together and Adenine & Thymine pair together because new nucleotides that are being _______________ by the cell bond with the exposed bases when DNA is split apart into two single strands

synthesized

In Chargaff's Experiment, ______________ & ______________ were 34% and ______________ & ______________ were 16%

Cytosine & Guanine, Adenine & Thymine

_________________ is the enzyme that prevents the DNA helix ahead of the replication fork from getting supercoiled as the DNA is opened up and acts by making temporary nicks in the helix to release the tension and sealing the nicks to avoid permanent damage

Toposiomerase

_____ _______________ is the key enzyme in DNA replication and is responsible for synthesizing DNA: they add nucleotides one by one to the growing DNA chain, incorporating only those that are complementary. 

DNA Polymerase

The ______________ strands of DNA causes each strand to be replicated at a different speed because multiple enzymes are needed in order to replicate the entire strand due to different directions 

antiparallel strands

DNA is made up of ______________ that have 3 parts, five-carbon sugar called deoxyribose, a phosphate group, and a nitrogen-containing base

nucleotides

__________ is an enzyme that makes RNA primer, or short stretched of nucleic acid complementary to the template, that provides a 3' end for DNA polymerase to work on.

(This primes DNA synthesis/getting it started)

Helicase

Why cannot DNA polymerase work on the 3' to 5' strand and start at 5'

3' to 5' polymerases would never work because the energy required would be way too high.

Coiled(______________) DNA allows for storage of DNA in our cells as chromosomes while uncondensed DNA allows access to the sequence of bases

condensed

The ___________ ___________ is the discontinuous 3' to 5' with fragments known as ___________ fragments because the DNA polymerase is moving away from the replication fork and must come off and reattach on the new exposed DNA

Lagging Stands, Okazaki Fragments

DNA replication is _______________, meaning that each strand in the DNA double helix acts as a template for the synthesis of a new complementary strand, with the new DNA containing an old strand and a new strand.

semiconservative

____ ________ is the enzyme that completes the Okazaki fragments in the lagging strand with complementary nucleotides

DNA ligase

Genes exist in alternate versions, or _______, that determine distinct traits 

alleles

___________ ___________ refers to differences in the genetic makeup of organisms in a population and necessary in natural selection

Genetic Variation

The three primary sources of genetic variation are ___________, _____, ___________ ___________

Mutations, Sex, Crossing Over

Genetic Variation occurs as alleles in gametes are separated and randomly united upon _______________

fertilization

When organisms sexually reproduce, ___________ - ________  during meiosis between the parent chromosomes occurs and bringing together new combination of genes

crossing-over

___________ ___________ promotes genetic variation by producing different gene combinations

Sexual Reproduction

An organism's ____ affects how it looks, behaves, and its physiology

DNA

Meiosis(increases|decreases) genetic variation though gene shuffling while the cell divides

increases 

True/False: Expose to specific chemicals or radiation can cause DNA to break down and mutate

True

_____ are inherited segments of DNA that contain for the production of proteins

Genes

________ is the process by which gametes(sex cells) are created

Meiosis

______ ___________ is the change in the DNA sequences and can sometimes and advantageous to an organism, but usually it neither gives advantage nor disadvantage and leads to genetic variation by altering genes and alleles in the population. This impacts an entire chromosome and changes the genotype

DNA mutation

Mutations happen because the ______ fails to copy accurately, _________ influences, and sex/crossing over 

DNA, external influences

A cell that is able to differentiate into all cell types within a body is called ___________

totipotent

How do stem cells know what type of cells to differentiate into

Signals from chemicals in the organism or from the environment determine which genes are expressed or repressed

__________ cells can differentiate to most cell types

Pluripotent

Position of a cell in the early _________ largely determines what cell type it will become

embryo

_______ ______________ is the altering pattern of gene expression and becoming a cell of a particular type. It is the process by which unspecialized cells become specialized by "turning on/off" specific genes. Certain gene expression is altered and the cell will develop specific structure perform specific functions.

Cell Differentiation

A _________ is a fertilized egg where every cell originates and divides repeatedly to produce an embryo. They are also totipotent. 

zygote

An unspecialized cell that can divide and give rise to different specialized cells is called ______ ______

stem cells

Cells types are different due to  _______ ______________, or instructions in DNA are converted into a function product like protein i.e. which genes are turned on and turned off

gene expression

_________ _________ is the production of proteins. DNA → RNA → protein; involves transcription and translation

Protein Synthesis

______ carries amino acids to the ribosomes during translation to help build amino acids

tRNA

In __________________, mRNA is decoded to specify the amino acids sequence of polypeptide(chain of amino acids). After the mRNA leaves the nucleus, it moves to ribosome, consisting of rRNA and proteins, which the ribosome reads the sequence of codons in mRNA and molecules of tRNA bringing amino acids from the cytoplasm to the ribosomes in the correct sequence

translation

In _____________, the DNA sequence of a gene is copied to make RNA molecules. It rewrite DNA sequence in a similar RNA alphabet that is converted to mRNA

transcription

A single-stranded nucleic acid that carries out the instructions coded in DNA is called _____

RNA

_________ ______ are structural units that make up proteins

Amino acids

A ________ is composed of one or more long chains of amino acids, the sequence of which corresponds to the DNA sequence of the gene that encodes it and is a functional product of genes. They do most of the work in cells and are required for the structure, function, and regulation of the body's tissues and organs

protein

______ carries information from DNA in the nucleus to ribosomes in the cytoplasm and originates from the nucleus

mRNA

____ is a structural component of the ribosome

rRNA

What are the 3 causes that change the change in traits?

1. Methylation of DNA: adding methyl groups to certain genes (inhibits protein synthesis)
2. DNA too tightly coiled around histones (Inhibits any proteins ability to access the DNA. Replication and Protein synthesis is stunted)
3. DNA being stuck in unwound position because of acetyl groups (Overproduction in protein synthesis)

True or False: Can the environment play a factor in epigenetics? 

True. Environmental pressures like famine, stress, lifestyle choices may lead to changes in how a person is able to make proteins

The concept of _______________ are the changes in gene expression that affect gene activity and function like how the body reads the DNA sequence, but don't change the entire DNA sequence. 

epigenetics

A _____________ is the combination of alleles (BB, Bb, bb)

genotype

What are the two type of melanin?

1. Pheomelanin, a reddish yellow color
2. Eumelanin, a brown black color

Pick the correct one: There is a (correlation/causation) between the intensity of UV radiation and latitude since UV radiation is intense along the equator and weakest at the poles. Stronger UV radiation is correlated with darker skin color 

correlation

True or False: Skin color is not an easily visible marker of variability

False: Skin color is an easily visible marker of variability because our lack of body hair and our variable skin color are some of the traits that set us apart from our closet primate relatives

The _______ gene codes fro a protein involved in the production of eumelanin(dark skin)

MCR1

_____/_____ frequency refers to the proportion of a population that carries one type of allele at a specific region on a chromosome. It is also a statistical way to determine the occurrence of a trait in a population

Gene/allele frequency

_______________ frequency is the number of individuals in a population that have a specific observable trait or phenotype and can be calculated by counting the number of times a particular phenotype appears in a population and dividing it by the total number of individuals in the population.

Phenotype frequency

A ___________ is all the individual organisms of the same species that live in the same geographical area

population

Data suggest that variation in human skin melanin production arose as different population ___________ biologically to different solar conditions around the world

adapted

Wavelengths of light are reflected or absorbed by pigment in skin known as ___________. This also protect us from the damaging affects of melanin.

melanin

The idea of ____________ ____________ occurs when some organisms have genetically based traits that cause them to survive and produce more offspring that other individuals. The best adapted individuals for the environment in population survive and produce the best offspring that are likewise well adapted

natural selection

An _______ are alternate forms of a gene that are found at the same place on a chromosome and can be represented by letters

allele

A ___________ is the physical trait that is expressed by the alleles (Brown vs. Blue eyes)

Phenotype

______ absorption is critical for the synthesis of vitamin D, a process that starts in the skin

UV-B

____ ____________ can penetrate living cells and cause mutations in DNA 

UV radiation 

Towards the poles, selective pressure for dark skin (to protect _________) decreases and selection for lighter skin shades( enable  _________ __ synthesis) increases because dark skin offers protection from damaging effects of UV radiation 

folate, vitamin D synthesis