Download cloze 4

1
Cloze 4-1
The Big Idea All organisms are composed of one or more_____.
Section 1 The Characteristics of Cells
Key Concept Cells function similarly in all living organisms.
Cells and Cell Discovery • Cells ________similarly in all living things.
• A ______is the smallest structural and functional unit of living things.
• In 1665, Robert Hooke built a _________and and observed box-like
structures in a sample of cork. He called the structures cells.
• Because animal cells lack cell_____, Hooke could not see them. He
believed that only plants and fungi were made of cells.
• In 1673, Dutch merchant Anton van Leeuwenhoek made a microscope
and observed swimming “_________” in a sample of pond scum.
• Today we call these single-celled organisms_________.
• Leeuwenhooek also observed blood cells from different animals and
was the first person to observe________.
Cells and Cell Theory • Nearly 100 years later, Matthias Schleiden, a plant scientists,
concluded
that all ________parts were made of cells.
• A year later, in 1839, Theodor Schwann concluded that all _________tissues were
made of cells.
• Schwann went on to write the first two parts of modern cell________:
• All organisms are made up of one or more cells.
• The cell is the basic unit of all living things.
• In 1858, Rudolf Virchow added the third part of the cell theory:
• All cells come from _________cells.
Cell Size • The vast majority of cells are too _______to be seen without a
microscope.
• If the volume of a cell becomes too large, the surface area of its
membrane will not be able to let in enough materials and let________ wastes.
• Cells must remain small to maintain a proper surface-area-to-volume_______.
Cell Membrane • Cells come in many shapes and sizes, and may be specialized for
different functions. But _____cells have some parts in common.
• All cells have a cell membrane. The cell membrane is a protective
layer that covers the cell’s surface and acts a ________.
• The cell membrane separates the cell’s contents from its____________.
• The cell membrane also controls the materials going ______and out of the cell.
Cytoplasm and Organelles • Most of the contents of a cell, including the fluid, is called
the___________.
• Organelles are part of the cytoplasm. Organelles are structures that
have specific _______inside the cell.
DNA and Nucleus • All cells have_____- (deoxyribonucleic acid) at some point in their
lives.
DNA is the genetic material that carries _________for making new cells.
• In eukaryotic cells, including plants and animals, the DNA is found
within the _________of the cell.
• The nucleus is an organelle ____________to hold the DNA. The nucleus
plays a role in growth, metabolism, and reproduction.
• __________have DNA, but do not have a nucleus. Their DNA floats free in the
cytoplasm.
• Human blood cells have a nucleus and DNA as they are growing. Once
mature, they _______their DNA and nucleus.
• Most cells, however, need DNA throughout their lives. The DNA
provides instructions for making ___________.
Two Kinds of Cells • Cells that do not have a nucleus are called prokaryotes. Bacteria
and __________ are prokaryotes.
• Prokaryotic DNA is a round molecule, twisted like a ___________band.
• Prokaryotes have cell walls. They lack the membrane-bound organelles
found in other organisms.
• Eukaryotes are organisms made up of cells that have a nucleus enclosed by
a_________.
• Eukaryotic cells are 10 times as large as prokaryotic cells, although
most eukaryotic cells are still__________.
• Eukaryotes have membrane-bound organelles to carry out the functions of the cell.
Section 2 Eukaryotic Cells
Key Concept Eukaryotic cells have organelles that perform
important functions.
Cell Wall • Eukaryotic cells have many organelles in common to carry out
important functions.
• _________ are eukaryotes that have some structures and organelles not seen in
animal cells.
• Plant cells have a rigid structure that surrounds the cell membrane
called the______ ______. Animal cells lack a cell wall.
Cell Membrane • All cells have a cell membrane made up of proteins and
_______________.
Answers: cells, cell, all, phospholipids , microscopic , microscope, membrane, small,
barrier, existing, lose , Bacteria, protests, DNA, out, plant, theory, animal, walls, bacteria,
animacules, ratio, into, nucleus, jobs, instructions, Plants , archaea, function, cytoplasm ,
rubber, surroundings, specialized, proteins, cell wall,