biology science exam Flashcards
(24 cards)
What is the function of the nucleus?
Contains DNA, controls cell activities
The nucleus is often referred to as the control center of the cell.
What is the main function of mitochondria?
Site of cellular respiration, makes energy (ATP)
Mitochondria are often called the powerhouse of the cell.
What do ribosomes produce?
Make proteins
Ribosomes can be found free in the cytoplasm or attached to the endoplasmic reticulum.
What is the role of cytoplasm in a cell?
Jelly-like fluid where reactions happen
The cytoplasm contains organelles and is the site for many metabolic processes.
Describe the structure of the phospholipid bilayer.
Double layer with hydrophilic heads facing out and hydrophobic tails facing in
This arrangement is crucial for membrane fluidity and function.
What does the fluid-mosaic model describe?
the fmm describes the cell membrane as a fluid and flexible structure composed of: phospolipids - form the bilayer foundation, proteins: embeded within or attache to the surface, cholestoral molecules - are interspersed between phospholipids, carbohydrates: are attached to proteins on the outer surface
Which molecules can pass through the cell membrane easily?
Small non-polar molecules
Larger or charged molecules require specific transport mechanisms.
What is the structure of DNA?
Double helix made of nucleotides (phosphate, sugar, base)
The four bases are adenine (A), thymine (T), cytosine (C), and guanine (G).
What pairs with adenine in DNA?
Thymine
Cytosine pairs with guanine.
Define a gene.
Section of DNA coding for a protein
Genes are the basic units of heredity.
What is a chromosome?
Long DNA molecule with genes
Humans have 46 chromosomes arranged in 23 pairs.
What is the difference between diploid and haploid?
2 Diploid daughter cells (2n): full set of chromosomes; 4 Haploid daughter cells (n): half set
Diploid cells are typical body cells, while haploid cells are gametes.
What happens during DNA replication?
DNA unzips, new nucleotides pair with exposed bases, forming two identical DNA molecules
This process is crucial for cell division.
List the four stages of mitosis.
- Prophase
- Metaphase
- Anaphase
- Telophase
Each stage is critical for proper cell division.
What is the purpose of DNA?
Stores genetic information, controls cell functions, passes traits to offspring
DNA is essential for inheritance and cellular operation.
What is a Punnett square used for?
To predict offspring genotypes and phenotypes from parents
It is a tool in genetics to visualize genetic crosses.
Define allele.
Different forms of a gene
Alleles can be dominant or recessive.
What is co-dominance?
Both alleles are expressed in heterozygotes
An example is the AB blood type.
What is the difference between germline and somatic mutations?
Germline: in gametes, passed to offspring; Somatic: in body cells, not inherited
Germline mutations can affect future generations.
What are the benefits of gene technologies?
Cure diseases, improve crops
Genetic engineering can lead to significant advancements in medicine and agriculture.
Describe natural selection.
Variation, isolation, adaptation, selection (VISS)
This process leads to evolution over time.
What is speciation?
Population splits, differences build up, new species forms
This process can occur due to various factors including geographical isolation.
What is divergent evolution?
Related species become different
This contrasts with convergent evolution, where unrelated species become similar.
List the evidence for evolution.
- Fossils
- Homologous structures
- Vestigial organs
These evidences support the theory of evolution.
