Genetic Material and Cell Signaling Flashcards

Flashcards covering key concepts in genetics, DNA structure, replication, expression, and cell signaling, structured for quick study.

How is genetic material organized in the nucleus?

DNA, nucleosomes, chromatin, chromosomes (condensed in mitosis)

What is DNA made of?

Nucleotides = phosphate + deoxyribose sugar + nitrogen base

What does antiparallel mean?

DNA strands run opposite directions (5’→3’ and 3’→5’)

What is noncoding DNA?

introns, repetitive sequences and regulatory regions that do not code for proteins

How do you find a complementary strand?

Tight, Off. Loose, On

What is chromatins structure

Loosely packed DNA

What is a chromosome?

Condensed DNA (visible in mitosis)

chromatin contains what

proteins + dna

What is a replication origin?

Site where DNA replication begins

What is a telomere?

Repetitive DNA at chromosome ends (protects DNA)

What are sister chromatids?

Identical copies of a chromosome

How is chromatin structure altered?

Chromatin remodeling + histone modification

How are DNA strands held together?

Hydrogen bonds between bases

___ melts faster than _____ because AT contains only 2 hydrogen bonds, while GC contains 3

AT, GC

What is a nucleosome?

DNA wrapped around histone proteins

Which DNA is transcriptionally active?

Euchromatin

What did Griffith prove with his experiment?

He discovered transformation — that genetic information can be transferred between bacteria, turning harmless cells into harmful ones.

What is a Barr body?

Inactive X chromosome in a females nucleus ensuring only one X is active

What is semiconservative replication?

Each new DNA has one old strand + one new strand

helicase _____, primase _________, and ligase ___________

unwinds, primes RNA, joins okazaki fragments

What is telomerase?

Enzyme that extends telomeres

What is depurination?

Loss of A or G base in dna

What is deamination?

Cytosine turns into uracil

What are thymine dimers?

UV-caused covalent bonds between T bases

__________ repair fixes errors in one DNA strand.

Mismatch

What is homologous recombination?

Accurate repair using sister chromatid

What is nonhomologous end joining?

Quick repair but error-prone

What happens if repair fails?

Diseases like cancer

When can nonhomologous end joining occur?

Any stage (but less accurate)

What are the steps of PCR?

Denaturation, annealing, extension

template strands are used to make _____ . the coding strand is the same as _____

RNA, RNA T → U

DNA is ____ stranded and has ______. RNA is ______ stranded and has _____.

double, deoxyribose. single, ribose

What is the difference between RNA polymerase and DNA polymerase?

RNA polymerase doesn’t need primer

Coding RNA includes ______. Noncoding RNA includes _______.

mRNA. tRNA, rRNA.

transcription in prokaryotes happens in the _______ while transcription in eukaryotes happens in the ______

cytoplasm, nucleus

What modifications does eukaryotic mRNA undergo?

5′ cap added (protects mRNA + helps ribosome bind), Poly-A tail added (stability + export from nucleus),

Splicing (removal of introns, joining exons)

What is gene expressions flow to get the final product? (protein)

going from DNA to RNA to protein

what is alternative splicing?

Different combinations of exons are joined to make different mRNAs after introns are spliced out

genetic code can be considered redundant because multiple __________ code for the same __________.

codons, amino acid

codons code for ________ and anticodons code for ____________

mRNA, tRNA

What is 'charged' tRNA?

tRNA attached to an amino acid

What is the function of ribosomes?

Makes proteins

What are the steps of translation?

Initiation, elongation, termination

What are initiation factors and release factors?

Start translation, stop translation

How do you predict codon and anticodon?

Use base pairing rules

Why is cell signaling important?

Respond to environment + coordinate functions

the type of cell signaling that includes paracrine signaling and synaptic signaling

local signaling

What are the steps of the signaling pathway?

Reception → transduction → response

Why do cells respond differently to signals?

Different receptors/proteins

What are major receptor types?

GPCR, RTK, intracellular

intracellular receptors have _______ signals, while surface receptors have ________ signals

hydrophobic signals, hydrophilic

What is signal amplification?

Small signal → large response

Why is it necessary to turn off signaling?

Prevent overactivation

What is an example of turning off signaling?

Dephosphorylation or ligand removal

What is the Ras pathway?

RTK → Ras → MAP kinase → gene expression

What happens if signaling mutates?

Can cause cancer/uncontrolled growth

What did Hershey and Chase prove?

They proved that DNA is the genetic material, not protein, using bacteriophages labeled with radioactive DNA and protein.

endocrine signaling is an example of what type of signaling

long distance signaling

the notch receptor pathway is an example of what type of signaling

direct contact

What is the brown structure (1) in a dividing cell image?

A condensed chromosome

1. What are the brown structures? Name them in both pictures:
2. What is their function?

Dividing cell: Chromosomes (condensed DNA, clearly visible)

Nondividing cell: Chromatin (loose, uncondensed DNA)

they both store and transmit DNA

which cell is transcribing more of its genes and why?

B because its lighter, meaning its not condensed, meaning transcription is active

One nucleosome is composed by

eight histone proteins, 2X H2A, H2B, H3 and H4

Who discovered the double-helix structure of DNA?

James Watson, Francis Crick and Wilkins and Franklin

Could you predict which of these DNA sequences will most

likely be part of replication origins?

A. 5’-ATTAAGTAAAACTTAA-3’

B. 5’-GGCGCGCTGCCCGAC-3

A because A-T are weaker than G-C

Telomerase is fully active in ________ cells because they ________, while it is not active in neurons because they ________.

actively dividing (stem), replicate DNA repeatedly and need to maintain telomeres, do not divide.

what would you expect from a eukaryote lacking telomerase?

a reduction of chromosome lengths in gametes

True or false, Neither Okazaki fragments, nor telomeres are found in prokaryotic DNA

true

it wouldn’t be better if dna polymerase III made no mistakes because it would likely __________ and require more energy. small mutations are _______ for genetic variation

slow replication, require more energy. beneficial.

when does homologous recombination most often occur?

shortly after a cells dna has been replicated before cell division because a sister chromatid is available as a template

based on this paternity test result:

paternity is not excluded

How does a ribosome know where to start and stop protein synthesis

Specific Codons in an mRNA

true or false, The ligands that bind intracellular receptors can be hydrophobic and a gas.

true

Testosterone is a ________ ________.

hydrophobic lipid.

it is a steroid hormone that can diffuse through membranes