Ch4 Genetics and Cellular Function Flashcards
DNA is our
Hereditary material
What does DNA help understand?
Hereditary traits and genetic disorders
What does DNA stand for?
Deoxyribonucleic acid (DNA)
How many DNA molecules are there in the nucleus?
46 DNA molecules in the nucleus
DNA are polymers of
Nucleotides
What do nucleotides consists of…
- Sugar: deoxyribose
- Phosphate group
- Nitrogen base
What are purines? And what are included in it?
Purines are double rings
- adenine (A) & guanine (G) are included in it
What are pyrimidines? And what are included in it?
Pyrimidines are single ring
- cytosine (C) & thymine (T) are included in it
What is commonly described as a double helix?
DNA
What is a double helix?
“Spiral staircase”
What is the double helix composed of?
- Backbone= phosphate groups + deoxyribose
- Connections between backbones= nitrogenous base
DNA base pairing:
What pairs with what?
G, A, C, T
- A & T
- C & G
What pairs the DNA base pairs?
Hydrogen bonds
What is chromatin?
Fine filamentous DNA material complex with proteins
What is a gene?
Sequence of DNA nucleotides that codes for one protein
Describe chromosomes?
2 parallel filaments of identical DNA; each= sister chromatid
- joined at centromere
- kinetochore -protein plaques
What is an RNA?
Smaller cousin of DNA (fewer bases)
Describe RNA structure
- One nucleotide chain (not double helix)
What is the function of RNA?
Interpret DNA code; makes complimentary copy of DNA that eventually codes for protein
What types of RNA are there?
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
In RNA, what does ribose replace?
Ribose replaces deoxyribose
In RNA, what does uracil replace?
Uracil replaces thymine
What is the process of protein synthesis?
DNA —> mRNA —> protein
What is the first and second arrow in:
DNA —> mRNA —> protein
DNA —> mRNA —> protein
First arrow is transcription
Second arrow is translation
Transcription is…
Where does transcription occur?
What is translation?
Where does translation occur?
Most occurs in cytoplasm
What does transcription do?
- Copies instructions from DNA to RNA
- Opens DNA helix; transcribes bases from 1 strand of DNA into pre-mRNA
- ^^^ if C on DNA, G is added to mRNA
- ^^^if A on DNA, U is added to mRNA, etc.
- Rewinds DNA helix
- Pre-mRNA is unfinished
Describe “nonsense” and “sense” when Pre-mRNA is unfinished (in transcription)
- “Nonsense”= introns removed by enzymes
- “Sense”= exons reconnected & exit nucleus = functional mRNA
Alternative splicing of mRNA
What does translation do?
-converts language of nucleotides into language of amino acids
Translation requires the participation of…
Transfer RNA (tRNA)
Describe tRNA
- one end has anticodon
- other end binds one amino acid
- each tRNA picks up specific amino acid from cytosol
What happens during peptide formation?
Describe protein processing and secreion
- translation is finished when amino acid sequence (primary structure) assembled
- to be functional, needs secondary & tertiary structure
chaperone proteins
older proteins that pick up new proteins, guide them in folding into proper shapes
What are chaperone proteins?
older proteins that pick up new proteins, guide them in folding into proper shapes
What are stress or heat-shock proteins?
- proteins produced in response to stress/heat
- help damaged protein fold back into correct functional shapes
What does DNA direct the synthesis of?
All proteins
-including enzymes that synthesize non-proteins
Not all cells make all ____ all the time
Not all cells make all PROTEINS all the time
-activators, such as hormones, may stimulate cell to make protein
Ex. prolactin to stimulate casein production
Before cell dividides, it…
it duplicate its DNA so it can give complete copy to each daughter cell
What are key players in cell replication?
What is the function of helicase?
Unwind DNA helix & create a replication force
What is the function of DNA polymerase?
What is the function of ligase?
Links any unbound nucleotides/helps link DNA strands together
What are the phases in the cell cycle?
- G1 phase
- S phase
- G2 phase
- M phase
- Interphase
- Mitosis
What is the G1 phase and what occurs during it?
G1 phase is the 1st gap phase
Ocurrances:
- growth, normal cell activity
- preparation to replicate DNA
What is the S phase and what occurs during it?
S phase is the synthesis phase
Occurances:
-duplication of DNA and centrioles
What is the G2 phase and what occurs during it?
G2 phase is the 2nd gap phase
Occurances:
- enzyme synthesis that occur in cell division
- repairing of DNA replication error
What is the M phase and what occurs during it?
M phase is the mitotic phase
Occurances:
-cell replicates its nucleus, then forms 2 new daughter cells
What phase(s) occur in interphase?
G1, S, & G2
What is the longest phase of cell replication?
Interphase
What are the functions of mitosis?
What are the phases of mitosis?
- Prophase (early= nucleus condenses - late= nuclear envelope breaks down)
- Metaphase (chromosomes line up at midline)
- Anaphase (spindle fibers pull sister chromatids to opposite poles of cell)
- Telophase (identical sets of chromosomes reach opposite ends of the poles and begin to decondense
What is cytokinesis?
Division of the cytoplasm
What is a karyotype?
A picture of a person’s chromosomes in order of size
- 2 of each pair - one from each parent
What is inheritance?
Genetic material divided my meiosis
What is a gamete?
Each gamete has one of each numbered _____
Each gamete (egg or sperm) has one of each numbered CHROMOSOME
What is a haploid?
One copy of each gene
What is a zygote?
When sperm and egg merge in fertilization
What is a diploid?
Two copies of each gene
What does a diploid lead to?
Genetic inheritance
What is an allele?
A variation of a gene/trait
What can alleles be?
Dominant and recessive
What is a dominant allele?
Trait expressed in body - you can see it
ex) eye color
What is a recessive allele?
A trait expressed in body if there is no dominant to “cover” it up (think i,i in punnet the square)
ex) blue eyes
What are homozygous and heterozygous?
What is homozygous?
2 identical alleles
ex) CC & cc
What is heterozygous?
Different alleles for a gene (Cc)
What is the difference between genotype and phenotype?
Genotype is what alleles you have in DNA for a trait vs Phenotype being what is expressed on outside of body (ex, cleft or uncleft chin)
Define multiple alleles
More than 2 allelic forms for trait
Ex) 3 alleles for ABO blood types: IA, IB, i
Define codominant
both alleles equally dominant
IA, IB = type AB blood
both phenotypically expressed; I recessive to each
Define incomplete dominance
phenotype intermediate betw/ traits each allele would have produced alone
What are sex-linked traits?
Traits carried on X & Y chromosomes
Recessive color blindness allele on __, no gene locus for trait on __, so red-green color blindness more common in ___ (____ is carrier)
Recessive color blindness allele on X, no gene locus for trait on Y, so red-green color blindness more common in MEN (MOTHER is carrier)
What are some sex-linked diseases or disorders?
- Duchenne Muscular dystrophy
- Fabry disease
- ALD
- Hemophilia
What is polygenic inheritance?
Many genes contributing to one phenotype
What is pleiotrophy?
one gene produces multiple phenotypic effects
Ex. Alkaptonuria, Sickle cell disease
What is penetrance?
The likelihood of a phenotype being expressed off a genotype /
What % of a population has a certain gene that actually shows the phenotype
What plays an important part in gene expression?
Environmental effects
What is cancer?
Uncontrolled mitosis
What is a malignant tumor?
Cancer
Define tumor angiogenesis
Blood vessels growing into tumor
How are cancers named?
Named for their tissue or origin
examples:
- carcinoma from epithelial tissues
- lymphoma from the lymph nodes
- sarcomas in bone
