1001 1-3 Flashcards
Where is DNA found in a eukaryotic cell?
cell nucleus (humans are eukaryotes)
chromosomes
a thread-like structure in the nucleus of a cell that contains DNA and proteins. Chromosomes are responsible for carrying genetic information from cell to cell, and are passed down from parents to their offspring.
containing nuclear DNA; 23 pairs (46)
in humans
Homologous chromosomes:
carry information for the same traits; 1
father, 1 from mother
Diploid #
full complement of chromosomes; found in somatic cells
Haploid #
half set of chromosomes;
found in gametes
Somatic Cell
The cells that make up your bodily tissues (”soma”)
● Each diploid somatic cell carries two copies of your genome
Gametic Cell
Your reproductive cells; in humans, sperm or eggs
● Each haploid gametic cell carries one copy of your genome
Eukaryote vs prokaryote
Eukaryotes have a nucleus and membrane-bound organelles, while prokaryotes do not. Prokaryotes are simpler, like bacteria, whereas eukaryotes include plants, animals, fungi, and protists.
Organelle
A tiny structure inside a cell that has a specific job, like a mini-organ.
Mitochondria
The powerhouse of the cell that makes energy from food.
Nucleus
Brain of the cell and holds DNA
DNA and its structure
DNA is a twisted ladder-shaped molecule (double helix) that carries genetic instructions for life.
DNA Function: replication
Process where DNA makes an exact copy of itself before a cell divides, ensuring each new cell gets the same genetic information.
Mitosis
cell division (duplication) for growth and repair
cell division for somatic cells
* results in two identical daughter cells
* diploid condition is retained (full complement of chromosomes)
Meiosis
cell division for gamete production
sex cells require only half the
number of chromosomes
* results in four daughter cells
* For males: all continue to become
sperm
* For females: one of the four continues
to become an ovum
when does DNA replication occur
before a cell divides
How does variation occur during
DNA replication?
It occurs when homologous chromosomes crossover and exchange genetic information during meiosis.
Mutations are the primary source of variation.
How do DNA replication and variation relate to natural selection?
DNA replication introduces genetic variation through mutations, which provides the raw material for natural selection to act upon and drive evolution.
What is Protein Synthesis
the process by which cells build proteins using the instructions encoded in DNA, involving transcription (DNA to mRNA) and translation (mRNA to protein).
DNA transcription
the process in which a segment of DNA is copied into messenger RNA (mRNA) by the enzyme RNA polymerase.
DNA translation
the process in which ribosomes synthesize proteins using mRNA as a template, converting nucleotide sequences into amino acid chains.
Step 1 of transcription: Initiation
RNA polymerase binds to the promoter region of DNA, unwinding the double helix.
Step 2 of transcription: Elongation
RNA polymerase moves along the DNA template strand, adding complementary RNA nucleotides to form mRNA.
Step 3 of transcription: Termination
Transcription stops when RNA polymerase reaches a termination sequence, releasing the mRNA strand.
